全文获取类型
收费全文 | 1914篇 |
免费 | 90篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 46篇 |
儿科学 | 68篇 |
妇产科学 | 143篇 |
基础医学 | 173篇 |
口腔科学 | 98篇 |
临床医学 | 162篇 |
内科学 | 408篇 |
皮肤病学 | 57篇 |
神经病学 | 193篇 |
特种医学 | 66篇 |
外科学 | 234篇 |
综合类 | 6篇 |
一般理论 | 1篇 |
预防医学 | 64篇 |
眼科学 | 25篇 |
药学 | 93篇 |
中国医学 | 2篇 |
肿瘤学 | 170篇 |
出版年
2022年 | 13篇 |
2021年 | 41篇 |
2020年 | 15篇 |
2019年 | 34篇 |
2018年 | 27篇 |
2017年 | 25篇 |
2016年 | 42篇 |
2015年 | 44篇 |
2014年 | 43篇 |
2013年 | 82篇 |
2012年 | 112篇 |
2011年 | 121篇 |
2010年 | 64篇 |
2009年 | 63篇 |
2008年 | 114篇 |
2007年 | 134篇 |
2006年 | 137篇 |
2005年 | 119篇 |
2004年 | 104篇 |
2003年 | 115篇 |
2002年 | 90篇 |
2001年 | 20篇 |
2000年 | 21篇 |
1999年 | 25篇 |
1998年 | 10篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 24篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1973年 | 9篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1970年 | 8篇 |
1968年 | 8篇 |
排序方式: 共有2009条查询结果,搜索用时 15 毫秒
31.
Karl M Potier M Schulman IH Rivera A Werner H Fornoni A Elliot SJ 《Endocrinology》2005,146(2):889-900
32.
Ike D. Tanabe M.D. Anthony DiTomaso M.D. Haim Pinkas M.D. Dobromir Pencev M.D. 《The American journal of gastroenterology》1995,90(3):504-505
We describe an unusual case of a 32-yr-old man who presented with massive GI hemorrhage as an initial manifestation of an ileal duplication cyst. The lesion was first revealed by visceral angiography during investigation of the bleeding source. At laparotomy, a large ileal duplication containing full-thickness gastric-type mucosa was identified. Ulceration of the ileal mucosa adjacent to the communicating orifice was found to be the source of bleeding. Duplications of the alimentary tract are rare congenital malformations. Patients usually present in infancy and childhood, although delayed complications can present in adulthood. This entity should be considered among other lesions that can cause massive GI hemorrhage not diagnosable by endoscopy. 相似文献
33.
BACKGROUND: The morbidity and mortality benefits of blood pressure (BP) control for the elderly is well documented. The cognitive consequences of hypertension control in this population, however, are still under debate. We aim to study the association between BP and cognitive performance in the elderly. Specifically, we explore 1) the possibility that BP is differentially associated with various cognitive domains; and 2) the utility of analyzing both BP and cognitive scores as continuous variables to unravel possible nonlinear associations. METHODS: Four hundred ninety-five community living 70 to 85 year olds completed eight cognitive tests that measured memory, concentration, visual retention, verbal fluency, and the mini-mental state examination (MMSE). The performance of each test was analyzed first by comparing four groups (normotensives, normalized hypertensives, untreated hypertensives, and treated but uncontrolled hypertensives). Then, using BP values as continuous variables, linear, U-curve, and J-curve associations were estimated. RESULTS: On all cognitive tests, except for verbal fluency, normotensives performed poorest, treated but uncontrolled hypertensives achieved the highest scores. The MMSE scores and the lighter concentration task were linearly related to BP; J-curve association was observed between memory and visual retention; prolonged concentration was related to pulse pressure alone. CONCLUSIONS: Low BP, as observed among the normotensive subjects, was associated with poor cognitive performance. Mild hypertension appeared to enhance cognitive functioning among the subjects of this study. Moreover, we found support for the hypothesis that the association between BP and different dimensions of cognition take on different patterns. 相似文献
34.
Eder L Zisman D Barzilai M Laor A Rahat M Rozenbaum M Bitterman H Feld J Rimar D Rosner I 《The Journal of rheumatology》2008,35(5):877-882
OBJECTIVE: To investigate the prevalence of subclinical atherosclerosis among patients with psoriatic arthritis (PsA). METHODS: Forty patients with PsA were enrolled. Controls were matched by age, sex, and atherosclerotic risk factors. All patients and controls underwent duplex scan of the carotid arteries. Carotid intima-media thickness (IMT) was evaluated and the presence of atherosclerotic plaques was recorded. The plaques were graded and carotid plaque index was calculated. RESULTS: Patients with PsA had a higher IMT (mean +/- standard deviation, 1.04 +/- 0.35 mm vs 0.88 +/- 0.29 mm in controls; p = 0.03), and had a higher carotid plaque index than did matched controls (2.3 +/- 2.6, compared to 1.12 +/- 2.09; p = 0.03). Multivariate analysis demonstrated that PsA status as well as age and triglyceride levels were associated with the presence of carotid plaque. Other traditional risk factors were more prevalent among patients with PsA; however, they were not statistically significant. CONCLUSION: Our study demonstrates that patients with PsA may have an increased prevalence of subclinical atherosclerosis. These findings may not be solely attributable to traditional risk factors alone. Special attention and strict control of atherosclerotic risk factors in patients with PsA is warranted. 相似文献
35.
Ofer Beharier Romina Plitman Mayo Tal Raz Kira Nahum Sacks Letizia Schreiber Yael Suissa-Cohen Rony Chen Rachel Gomez-Tolub Eran Hadar Rinat Gabbay-Benziv Yuval Jaffe Moshkovich Tal Biron-Shental Gil Shechter-Maor Sivan Farladansky-Gershnabel Hen Yitzhak Sela Hedi Benyamini-Raischer Nitzan D. Sela Debra Goldman-Wohl Ziv Shulman Ariel Many Haim Barr Simcha Yagel Michal Neeman Michal Kovo 《The Journal of clinical investigation》2021,131(13)
BACKGROUNDThe significant risks posed to mothers and fetuses by COVID-19 in pregnancy have sparked a worldwide debate surrounding the pros and cons of antenatal SARS-CoV-2 inoculation, as we lack sufficient evidence regarding vaccine effectiveness in pregnant women and their offspring. We aimed to provide substantial evidence for the effect of the BNT162b2 mRNA vaccine versus native infection on maternal humoral, as well as transplacentally acquired fetal immune response, potentially providing newborn protection.METHODSA multicenter study where parturients presenting for delivery were recruited at 8 medical centers across Israel and assigned to 3 study groups: vaccinated (n = 86); PCR-confirmed SARS-CoV-2 infected during pregnancy (n = 65), and unvaccinated noninfected controls (n = 62). Maternal and fetal blood samples were collected from parturients prior to delivery and from the umbilical cord following delivery, respectively. Sera IgG and IgM titers were measured using the Milliplex MAP SARS-CoV-2 Antigen Panel (for S1, S2, RBD, and N).RESULTSThe BNT162b2 mRNA vaccine elicits strong maternal humoral IgG response (anti-S and RBD) that crosses the placenta barrier and approaches maternal titers in the fetus within 15 days following the first dose. Maternal to neonatal anti-COVID-19 antibodies ratio did not differ when comparing sensitization (vaccine vs. infection). IgG transfer ratio at birth was significantly lower for third-trimester as compared with second trimester infection. Lastly, fetal IgM response was detected in 5 neonates, all in the infected group.CONCLUSIONAntenatal BNT162b2 mRNA vaccination induces a robust maternal humoral response that effectively transfers to the fetus, supporting the role of vaccination during pregnancy.FUNDINGIsrael Science Foundation and the Weizmann Institute Fondazione Henry Krenter. 相似文献
36.
BACKGROUND: Several reports have suggested that early chest tube drainage (CTD) may not be necessary in the treatment of severe pleural empyema (PE) in pediatric patients if appropriate antibiotic therapy and supportive care are provided. OBJECTIVES: A prospective open study to compare the short-term course of two treatment protocols of severe PE in pediatric patients. STUDY DESIGN: One group of 32 patients was treated with early insertion of a chest tube for CTD, and a second group of 35 patients was treated by a repeated ultrasound-guided needle thoracocentesis (RUSGT). The severity of the empyema was assessed by chest radiograph, the amount of fluid drained, the number of days the patient had experienced a fever, and the duration of antibiotic treatment. RESULTS: No significant differences were found between the two groups (RUSGT vs CTD) in all of the following measurements: mean (plus minus SD) duration of a temperature > or = 39 degreesC, 6.2 +/- 2.4 vs 6.5 +/- 1.8 days, respectively; mean duration of a temperature > or = 38 degreesC, 9 +/- 3.9 vs 8.2 +/- 4.5 days, respectively; fluid drained, 35.1 + 23.8 vs 30 +/- 28.2 mL/kg, respectively; duration of antibiotic treatment, 30 +/- 13.2 vs 30.2 +/- 7.3 days, respectively; and length of hospitalization and home IV treatment, 22 +/- 7.6 vs 24.2 +/- 7.5 days, respectively. A failure to respond to treatment occurred in three patients in the RUSGT-treated group and in five patients in the CTD-treated group. The failure to respond occurred in the RUSGT-treated group only in those patients with very large empyemas that caused mediastinal deviation. CONCLUSION: The treatment of PE by RUSGT is as efficacious as CTD, unless PE causes mediastinal deviation. 相似文献
37.
Higher gastric mucin secretion and lower gastric acid output in first-degree relatives of gastric cancer patients 总被引:1,自引:0,他引:1
Vilkin A Levi Z Morgenstern S Shmuely H Gal E Hadad B Hardi B Niv Y 《Journal of clinical gastroenterology》2008,42(1):36-41
BACKGROUND: Patients infected by Helicobacter pylori who have first-degree relatives with gastric cancer have an 8-fold increased risk of developing gastric cancer themselves. Mucins are high-molecular-weight glycoproteins that play a cardinal role in the protective mechanism of the gastric epithelium. AIM: To study gastric acid and mucin secretion in dyspeptic patients with and without a family history of gastric cancer and H. pylori infection. MATERIALS AND METHODS: Twenty-six dyspeptic patients underwent esophago-gastro-duodenoscopy, gastric biopsies, and acid and mucin secretory tests. The sample was divided by family history of gastric cancer and H. pylori status. RESULTS: Patients who were infected by H. pylori had a significantly higher degree of inflammation than those who were not. H. pylori-positive patients with a positive family history had a lower basal and maximal gastric acid output than infected patients with no family history and noninfected controls, and a higher basal and maximal mucin output than infected patients with no family history. MUC5AC was the major mucin species expressed in gastric juice. CONCLUSIONS: In patients with relatives with gastric cancer, H. pylori infection is associated with a more severe inflammatory reaction consisting of decreased gastric acid secretion and increased mucin secretion. 相似文献
38.
Actin polymerization and development of hyperactivated (HA) motility are two processes that take place during sperm capacitation. Actin polymerization occurs during capacitation and prior to the acrosome reaction, fast F-actin breakdown takes place. The increase in F-actin during capacitation depends upon inactivation of the actin severing protein, gelsolin, by its binding to phosphatydilinositol-4, 5-bisphosphate (PIP2) and its phosphorylation on tyrosine-438 by Src. Activation of gelsolin following its release from PIP2 is known to cause F-actin breakdown and inhibition of sperm motility, which can be restored by adding PIP2 to the cells. Reduction of PIP2 synthesis inhibits actin polymerization and motility, while increasing PIP2 synthesis enhances these activities. Furthermore, sperm demonstrating low motility contained low levels of PIP2 and F-actin. During capacitation there was an increase in PIP2 and F-actin levels in the sperm head and a decrease in the tail. In spermatozoa with high motility, gelsolin was mainly localized to the sperm head before capacitation, whereas in low motility sperm, most of the gelsolin was localized to the tail before capacitation and translocated to the head during capacitation. We also showed that phosphorylation of gelsolin on tyrosine-438 depends upon its binding to PIP2. Stimulation of phospholipase C, by Ca2+-ionophore or by activating the epidermal-growth-factor-receptor, inhibits tyrosine phosphorylation of gelsolin and enhances enzyme activity. In conclusion, these data indicate that the increase of PIP2 and/or F-actin in the head during capacitation enhances gelsolin translocation to the head. As a result, the decrease of gelsolin in the tail allows the maintenance of high levels of F-actin in this structure, which is essential for the development of HA motility.To acquire the ability to fertilize the egg, mammalian spermatozoa must undergo several biochemical and morphological changes in the female reproductive tract, collectively called capacitation. These changes include cAMP/PKA activation, cholesterol efflux from the plasma membrane, PKA-dependent protein tyrosine phosphorylation, actin polymerization and the development of HA motility.1,2 In a recent study we suggested a mechanism by which the Ser/Thr targeting PKA can lead to Tyr phosphorylation of proteins in the capacitation process. We showed that PKA activates Src which, in turn, inhibits the phosphatase PP1, leading to CaMKII activation, which activates Pyk2 to phosphorylate phosphatidyl-inositol-3-kinase on tyr-458.3We have shown elsewhere that actin polymerization must take place in order to capacitate spermatozoa while very fast depolymerization of F-actin occurs prior to the acrosome reaction.4 It has been suggested that an increase in F-actin during capacitation creates a network in the sperm head between the plasma membrane and the outer acrosomal membrane, and the dispersion of this F-actin must occur to enable acrosomal exocytosis.4,5,6,7 The increase in F-actin in the sperm tail during capacitation is important for the development of HA motility.8 The latter is characterized by an increase in flagellar bending amplitude and an increase in average lateral head movement.9,10 It was shown that the efficiency of HA sperm to penetrate the egg is much higher than non-HA sperm.11 Sperm motility and HA motility are mediated by PLD-dependent actin polymerization.8 It is known that phosphatidylinositol 4,5-bisphosphate (PIP2) is a cofactor for PLD activation in many cell types.12,13,14,15,16 PIP2 comprises only 1% of plasma membrane phospholipids, however its extraordinary versatility puts it in the center of plasma membrane dynamics governing cell motility, adhesion, endo- and exocytosis.17,18PIP2 serves as an effector of several proteins such as Myristoylated alanine-rich C-kinase substrate (MARCKS), gelsolin, PLD and PI3K. These proteins are present in spermatozoa19,20 and are involved in the regulation of sperm capacitation and/or the acrosome reaction. PIP2 binds gelsolin and release it from actin filaments ends, exposing sites for actin assembly.21 We have shown that the release of bound gelsolin from PIP2, causes rapid Ca2+-dependent F-actin depolymerization as well as an increased acrosome reaction.22 We have also shown that PIP2 and gelsolin are involved in regulating sperm motility and the development of HA motility.23 相似文献
39.
40.
Diagnosis and treatment of urinary tract complications in Crohn's disease: an experience over 15 years. 总被引:3,自引:0,他引:3
Haim Ben-Ami Yeoshua Ginesin Doron M Behar Doron Fischer Yeouda Edoute Alexandra Lavy 《Journal canadien de gastroenterologie》2002,16(4):225-229
BACKGROUND: Urinary tract complications in Crohn's disease are common but treatable, and often present diagnostic and therapeutic dilemmas. PURPOSE: To determine the incidence of urinary tract complications in patients with Crohn's disease in Israel and to report an experience over 15 years of patients with Crohn's disease, with the aim of illustrating the diverse patterns of presentation, and thereby broadening the approach to diagnosis and treatment. METHODOLOGY: Clinical and radiological findings of 312 patients with Crohn's disease were reviewed. RESULTS: Simple cystitis was the most common problem, occurring in 51 patients. The problem seldom required hospitalization and was instead managed in the ambulatory setting. A review revealed that 22 patients with urinary tract complications required hospitalization. Six patients had ileovesical fistulas. In one patient, the colon was also affected. In another patient, radiological and endoscopic studies failed to identify the fistula, which was confirmed during surgery. All six patients were treated surgically. Four patients had ureteral obstructions and hydronephrosis, three of whom responded well to conservative treatment. In one patient, the affected ileal segment was resected. Four patients suffered from retroperitoneal abscess accompanied by urinary symptoms. Twelve patients developed right kidney stones. All of the patients suffered from long-standing Crohn's disease with bowel resection. Surprisingly, most of the severe complications occurred in men, although 70% of the patients were women. CONCLUSIONS: Based on these findings, urological complications are not rare in patients with Crohn's disease, and necessitate a high degree of diligence and periodic urological evaluation. 相似文献