首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5418篇
  免费   226篇
  国内免费   28篇
耳鼻咽喉   73篇
儿科学   136篇
妇产科学   109篇
基础医学   539篇
口腔科学   120篇
临床医学   397篇
内科学   1493篇
皮肤病学   19篇
神经病学   637篇
特种医学   306篇
外科学   776篇
综合类   11篇
预防医学   176篇
眼科学   55篇
药学   243篇
中国医学   9篇
肿瘤学   573篇
  2024年   8篇
  2023年   69篇
  2022年   114篇
  2021年   228篇
  2020年   117篇
  2019年   127篇
  2018年   197篇
  2017年   119篇
  2016年   158篇
  2015年   167篇
  2014年   255篇
  2013年   275篇
  2012年   456篇
  2011年   420篇
  2010年   214篇
  2009年   246篇
  2008年   347篇
  2007年   335篇
  2006年   349篇
  2005年   327篇
  2004年   268篇
  2003年   252篇
  2002年   190篇
  2001年   40篇
  2000年   38篇
  1999年   40篇
  1998年   35篇
  1997年   27篇
  1996年   18篇
  1995年   21篇
  1994年   11篇
  1993年   15篇
  1992年   20篇
  1991年   23篇
  1990年   12篇
  1989年   13篇
  1988年   16篇
  1987年   7篇
  1986年   11篇
  1985年   12篇
  1984年   14篇
  1983年   6篇
  1982年   7篇
  1980年   7篇
  1979年   5篇
  1978年   4篇
  1976年   2篇
  1972年   4篇
  1971年   2篇
  1967年   2篇
排序方式: 共有5672条查询结果,搜索用时 15 毫秒
71.
PURPOSE This retrospective study evaluates the effect of abdominal hysterectomy on patients affected by descending perineum syndrome. METHODS Eighty-nine female patients affected by descending perineum syndrome and one group of 10 healthy women with normal bowel habits were studied retrospectively. Thirty-two descending perineum syndrome patients (Group 1) had received an abdominal hysterectomy for benign diseases, while 57 descending perineum syndrome patients (Group 2) had not undergone this surgery. All 99 subjects underwent clinical evaluation, computerized anorectal manometry, and defecography. RESULTS Dyschezia was found predominantly in Group 2 subjects (P < 0.05). Fecal incontinence was significantly higher in Group 1 than in Group 2 (P < 0.05). The worst anal resting pressure was found in the incontinent Group 1 patients (P < 0.01). Rectoanal intussusception was a significant defecographic sign in Group 1 subjects (P < 0.05). CONCLUSIONS Clinical evaluation and instrumental data suggested a possible link between fecal incontinence and abdominal hysterectomy in patients affected by descending perineum syndrome.  相似文献   
72.
To study the effects of sampling through cardiac catheters on indices of platelet function, we measured the levels of platelet factor 4 (PF4), beta thromboglobulin (BTG), and platelet aggregate ratio (PAR) in 10 patients with atrioventricular accessory pathway (AVNAP), six patients with primary pulmonary hypertension (PPH), and six patients with critical narrowing of the left anterior descending artery (LAD). In AVNAP and LAD patients samples were drawn simultaneously from a peripheral vein, coronary sinus, and brachial artery; in AVNAP patients samples were also obtained from the axillary vein before the coronary sinus was entered. In PPH patients samples were drawn from pulmonary artery, aorta, and a peripheral vein; in these patients the effects of an intravenous infusion of prostacyclin (PGl2) (2 to 8 ng/kg/min) on PF4, BTG, and PAR were also studied at all sampling sites. In all patients arterial, coronary sinus, pulmonary arterial, and axillary venous levels of PF4, BTG, and PAR significantly exceeded those measured in the peripheral vein. PGl2 infusion resulted in a significant decrease of PF4 at all sampling sites, while no consistent BTG changes were observed and PAR levels did not decrease in the peripheral vein. Although a considerable interpatient variability in PF4 levels was observed, a significant (r = 0.91) correlation was found in patients with AVNAP between simultaneous coronary sinus and arterial PF4 levels. The value of PF4 coronary sinus-arterial difference in LAD patients was consistently higher than that calculated in AVNAP patients (54.5 ± 28.9 vs 4.2 ± 3.8 ng/ml). In conclusion: (1) a considerable and variable degree of platelet activation occurs with catheter sampling, preventing the measurement of absolute levels of platelet metabolites; (2) among the indices examined PF4 appears the most sensitive for detecting changes in platelet activity; and (3) the measurement of coronary sinus-arterial PF4 differences may provide information on directional changes in transcardiac platelet behavior.  相似文献   
73.
Purpose  Some patients, having undergone sphincter-saving operations for rectal cancer, may suffer from fecal incontinence. This study was designed to evaluate the results of rehabilitative treatment in patients with fecal incontinence after sphincter-saving operations and to identify the negative factors that influence therapeutic success. Methods  Between January 2000 and June 2007, 88 incontinent patients (54 women; age range, 47–73 years; 69 had received a low anterior rectal resection; 19 a straight coloanal anastomosis) were included in the study. After a preliminary clinical evaluation, including the Wexner Incontinence Scale score, anorectal manometry was performed. All 88 patients underwent rehabilitative treatment according to the “multimodal rehabilitative program” for fecal incontinence. At the end of program, all 88 patients were reassessed by means of a clinical evaluation and anorectal manometry; their results were compared with the clinical and manometric data from ten healthy control subjects. Postrehabilitative Wexner Incontinence Scale scores were used for an arbitrary schedule of patients divided into three classes: Class I, good (score ≤3); Class II, fair (score >3 to ≤6); Class III, poor (score >6). Results  After rehabilitation, there was a significant improvement in the overall mean Wexner Incontinence Scale score (P < 0.03) for both surgical operation types (low anterior rectal resection: P < 0.05; coloanal anastomosis: P < 0.02). Only 21 patients (23.8 percent) were symptom-free, and 37 (42 percent) were considered Class III. A significant postrehabilitative direct correlation was found between: 1) Wexner Incontinence Scale score and degree of genital relaxation (rρ s 0.78; P < 0.001); 2) Wexner Incontinence Scale score and irradiation (rρ s 0.72; P < 0.01); and 3) Wexner Incontinence Scale score and pelvic (rρ s 0.65; P < 0.01) or anal surgery (rρ s 0.68; P < 0.01). No significant differences were found between prerehabilitative and postrehabilitative anal pressures in low anterior rectal resection and coloanal anastomosis patients. Conclusions  After rehabilitation, some patients become symptom-free, many patients show an improvement in the Wexner Incontinence Scale score, and others exhibit the highest grades of fecal incontinence. Genital relaxation, radiotherapy, and previous pelvic, and/or anal surgery are impeding factors to rehabilitative success.  相似文献   
74.
75.
Tick-borne encephalitis virus (TBEV) is an emerging human pathogen that causes potentially fatal disease with no specific treatment. Mouse monoclonal antibodies are protective against TBEV, but little is known about the human antibody response to infection. Here, we report on the human neutralizing antibody response to TBEV in a cohort of infected and vaccinated individuals. Expanded clones of memory B cells expressed closely related anti-envelope domain III (EDIII) antibodies in both groups of volunteers. However, the most potent neutralizing antibodies, with IC50s below 1 ng/ml, were found only in individuals who recovered from natural infection. These antibodies also neutralized other tick-borne flaviviruses, including Langat, louping ill, Omsk hemorrhagic fever, Kyasanur forest disease, and Powassan viruses. Structural analysis revealed a conserved epitope near the lateral ridge of EDIII adjoining the EDI–EDIII hinge region. Prophylactic or early therapeutic antibody administration was effective at low doses in mice that were lethally infected with TBEV.  相似文献   
76.
The term "neuronal ceroid lipofuscinosis" (NCL) describes a complex of inherited neurodegenerative conditions associated with storage of lipopigments in brain tissue. In 1989 Dyken proposed a classification of NCL based on the age, clinical symptoms, and ultrastructural aspects of the lipopigments. At the ultrastructural level it is possible to distinguish 5 different patterns of osmiophilic lipopigments: usual lipofuscin, fingerprint deposits, granular profiles, curvilinear bodies, and microtubular aggregates. The concept that each ultrastructural pattern was the counterpart of a specific clinical type has been proved not to be true. Advances in molecular genetic techniques have allowed the identification of defective genes and their protein products in several NCL clinical forms. Ceroid lipofuscin deposits may be ultrastructurally observed not only in neuronal cells, but also in several other sites, such as trophoblastic cells, thus permitting prenatal diagnosis. In spite of recent advances in immunohistochemical identification of biochemical markers, the ultrastructural identification of lipofuscinic pigments remains the gold standard to identify NCL, together with clinical aspects and respective gene defects. This study describes the ultrastructural aspects observed in 8 cases of NCL syndromes (3 juvenile, 3 infantile, 1 late infantile, and 1 congenital clinical form). In these patients, genetic analysis was also performed.  相似文献   
77.
78.
This is a case of 62 years old Caucasian treatment‐naïve patient who developed a severe acute hepatitis B infection soon after a trip to Thailand. The infection was due to genotype C HBV which was found to be resistant to lamivudine and telbivudine. The patient was treated with tenofovir resulting in complete suppression of viral replication and complete clinical and laboratory remission of acute hepatitis. Later the patient also developed seroconversion of HBeAg to anti‐HBe and of HBsAg to anti‐HBs. This case demonstrates that mutations of HBV polymerase associated with lamivudine, telbivudine, and adefovir resistance can be present also in untreated patients with severe acute hepatitis B. This suggests that in the clinical context, which represents a life threatening condition, a baseline resistance‐testing should be an additional marker in the diagnostic evaluation process. Finally, this case report seems to support the use of tenofovir for the immediate treatment of severe acute hepatitis B. J. Med. Virol. 85:210–213, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   
79.

Background

Lithium is recommended as a first-line treatment for Bipolar Disorder (BD). Thyroid and renal alterations are well known lithium side-effects, while effects on parathyroids are less studied. The aim of this case-control cross-sectional study is to compare parathyroid hormone (PTH) and calcium levels in lithium-exposed bipolar patients and in subjects who had never been exposed to lithium.

Methods

112 BD patients were enrolled, 58 on lithium since at least 1 month (mean exposure 60.8±74.8 months) and 54 in the control group. Blood exams included complete blood count, PTH, total and ionized calcium, TSH, T3 and T4, creatinine, urea, sodium and potassium, and lithium serum levels. The Student's t-test and the Pearson's Chi-square test were used for bivariate analyses. A linear regression model was used to analyze the relationship between the duration of exposure to lithium and PTH and calcium levels.

Results

PTH and ionized calcium levels were significantly higher in lithium-exposed patients; the proportions of subjects with hyperparathyroidism (8.6%) and hypercalcaemia (24.1%) were significantly greater in lithium-exposed patients. The linear regression analyses showed a significant effect of exposure to lithium in months on ionized calcium levels but not on PTH levels.

Limitations

Given the cross-sectional design of the study we could not identify the exact time of occurrence of hyperparathyroidism.

Conclusions

Our results indicate that lithium-associated stimulation of parathyroid function is more common than assumed to date. Among parameters to be evaluated prior to lithium implementation and during long-term lithium maintenance, calcium (and eventually PTH) should be added.  相似文献   
80.
BackgroundThe association of age with coronary plaque dynamics is not well characterized by coronary computed tomography angiography (CCTA).MethodsFrom a multinational registry of patients who underwent serial CCTA, 1153 subjects (61 ± 5 years old, 61.1% male) were analyzed. Annualized volume changes of total, fibrous, fibrofatty, necrotic core, and dense calcification plaque components of the whole heart were compared by age quartile groups. Clinical events, a composite of all-cause death, acute coronary syndrome, and any revascularization after 30 days of the initial CCTA, were also analyzed. Random forest analysis was used to define the relative importance of age on plaque progression.ResultsWith a 3.3-years’ median interval between the two CCTA, the median annual volume changes of total plaque in each age quartile group was 7.8, 10.5, 10.8, and 12.1 mm3/year and for dense calcification, 2.5, 4.6, 5.4, and 7.1 mm3/year, both of which demonstrated a tendency to increase by age (p-for-trend = 0.001 and < 0.001, respectively). However, this tendency was not observed in any other plaque components. The annual volume changes of total plaque and dense calcification were also significantly different in the propensity score-matched lowest age quartile group versus the other age groups as was the composite clinical event (log-rank p = 0.003). In random forest analysis, age had comparable importance in the total plaque volume progression as other traditional factors.ConclusionsThe rate of whole-heart plaque progression and dense calcification increases depending on age. Age is a significant factor in plaque growth, the importance of which is comparable to other traditional risk factors.Clinical trial registrationURL: http://www.clinicaltrials.gov. Unique identifiers: NCT02803411.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号