全文获取类型
收费全文 | 18808篇 |
免费 | 1269篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 216篇 |
儿科学 | 440篇 |
妇产科学 | 346篇 |
基础医学 | 2587篇 |
口腔科学 | 319篇 |
临床医学 | 1631篇 |
内科学 | 4855篇 |
皮肤病学 | 410篇 |
神经病学 | 1621篇 |
特种医学 | 613篇 |
外科学 | 2677篇 |
综合类 | 239篇 |
一般理论 | 8篇 |
预防医学 | 1395篇 |
眼科学 | 411篇 |
药学 | 1132篇 |
中国医学 | 78篇 |
肿瘤学 | 1173篇 |
出版年
2023年 | 131篇 |
2022年 | 330篇 |
2021年 | 545篇 |
2020年 | 306篇 |
2019年 | 448篇 |
2018年 | 515篇 |
2017年 | 342篇 |
2016年 | 364篇 |
2015年 | 451篇 |
2014年 | 619篇 |
2013年 | 841篇 |
2012年 | 1332篇 |
2011年 | 1350篇 |
2010年 | 773篇 |
2009年 | 667篇 |
2008年 | 1127篇 |
2007年 | 1196篇 |
2006年 | 1177篇 |
2005年 | 1105篇 |
2004年 | 1007篇 |
2003年 | 959篇 |
2002年 | 952篇 |
2001年 | 132篇 |
2000年 | 117篇 |
1999年 | 162篇 |
1998年 | 208篇 |
1997年 | 169篇 |
1996年 | 169篇 |
1995年 | 122篇 |
1994年 | 119篇 |
1993年 | 101篇 |
1992年 | 105篇 |
1991年 | 104篇 |
1990年 | 90篇 |
1989年 | 73篇 |
1988年 | 84篇 |
1987年 | 93篇 |
1986年 | 75篇 |
1985年 | 95篇 |
1984年 | 100篇 |
1983年 | 94篇 |
1982年 | 111篇 |
1981年 | 124篇 |
1980年 | 107篇 |
1979年 | 67篇 |
1978年 | 77篇 |
1977年 | 87篇 |
1976年 | 64篇 |
1974年 | 53篇 |
1973年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Acetylcholinesterase Adaptation to Voluntary Wheel Running is Proportional to the Volume of Activity in Fast, but not Slow, Rat Hindlimb Muscles 总被引:4,自引:0,他引:4
Victor Gisiger Manon Bélisle Phillip F. Gardiner 《The European journal of neuroscience》1994,6(5):673-680
Chronic enhancement of neuromuscular activity by forced exercise training programmes results in selective adaptation of the G4 acetylcholinesterase (AChE) molecular form in hindlimb fast muscles of the rat, with only minor and non-selective AChE changes in the soleus. In order to shed further light on the physiological significance of this G4 adaptation to training, we turned to a voluntary exercise model. The impact of 5 days and 4 weeks of voluntary wheel cage running on AChE molecular forms was examined in four hindlimb fast muscles and the slow-twitch soleus from two rat strains. Inbred Fisher and Sprague– Dawley rats, placed in live-in wheel cages, exercised spontaneously for distances which progressively increased up to an average of ∼3 and 18 km/day, respectively, by the end of week 4. Fast muscles responded to this voluntary activity by massive G4 increases (up to 420%) with almost no changes in A12 , so that by week 4 the tetramer became the main AChE component of these muscles. The additional G4 was composed primarily of amphiphilic molecules, suggesting a membrane-bound state. The G4 content of fast muscles was highly correlated with the distance covered by the rats during the 5 days before they were killed ( r = 0.850-0.879, P < 0.001 in three muscles). The soleus muscle, in turn, responded to wheel cage activity by a marked selective reduction of its asymmetric forms—up to 45% for A12 . This A12 decline, already maximal by day 5 of wheel cage running, showed no relationship with the distance covered. The present results constitute strong new evidence suggesting that the role of AChE in neuromuscular transmission is not limited solely to the rapid inactivation of just-released acetylcholine. 相似文献
43.
John A. Procaccino M.D. Ian C. Lavery M.D. Victor W. Fazio M.D. John R. Oakley M.D. 《Diseases of the colon and rectum》1991,34(9):784-789
From 1961 to 1989, 67 patients underwent various surgical procedures for psoas abscess. Retrospective analysis was undertaken in an effort to determine optimal surgical therapy. Forty patients were cured with one operation. Twenty-one patients required two operations, four patients required three operations, and two patients required more than three operations. The reason for failure of treatment was failure to resect the diseased bowel or to drain the psoas abscess adequately. A technique to recognize and treat the abscess definitively will be illustrated. The most common etiologies were Crohn's disease in 49 patients, postoperative sepsis in eight patients, and complications of renal disease in four patients. The length of hospital stay ranged from 5 to 392 days (mean, 26 days). There were two deaths. Failure to recognize and treat psoas abscess results in considerable morbidity.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, St. Louis, Missouri, April 29 to May 4, 1990. 相似文献
44.
Francisca M Vera Juan M Manzaneque Enrique F Maldonado Gabriel A Carranque Victor M Cubero Maria J Blanca Miguel Morell 《Medical science monitor》2007,13(12):CR560-CR566
BACKGROUND: The aim of the present study was to analyze the effects of a qigong training program on blood biochemical parameters. MATERIAL/METHODS: Twenty-nine healthy subjects participated in the study of whom 16 were randomly assigned to the experimental group and 13 to the control. The experimental subjects underwent daily qigong training for one month. Blood samples for the quantification of biochemical parameters (total cholesterol, HDL, LDL, triglycerides, phospholipids, GOT, GPT, GGT, urea, creatinine) were taken before and after the training program. As statistical analysis, ANCOVA was performed. RESULTS: Statistically significant differences were found showing that the experimental group had lower serum levels of GOT (glutamic-oxaloacetic transaminase), GPT (glutamic-pyruvic transaminase), and urea and that there was a trend towards significance in GGT (gamma-glutamyltransferase). CONCLUSIONS: This study demonstrates that after practicing qigong for the short period of one month, noteworthy changes in several blood biochemical parameters were induced. While it is tempting to speculate on the relevance and implications of these biochemical variations, further investigation is needed to elucidate the scope of these findings. 相似文献
45.
46.
John J Doyle Alfred I Neugut Judith S Jacobson Victor R Grann Dawn L Hershman 《Journal of clinical oncology》2005,23(34):8597-8605
PURPOSE: Adjuvant chemotherapy, especially with anthracyclines, is known to cause acute and chronic cardiotoxicity in breast cancer patients. We studied the cardiac effects of chemotherapy in a population-based sample of breast cancer patients aged > or = 65 years with long-term follow-up. PATIENTS AND METHODS: In the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we analyzed treatments and outcomes among women > or = 65 years of age who were diagnosed with stage I to III breast cancer from January 1, 1992 to December 31, 1999. Propensity scores were used to control for baseline heart disease (HD) and other known predictors of chemotherapy, and Cox proportional hazards models were used to estimate the risk of cardiomyopathy (CM), congestive heart failure (CHF), and HD after chemotherapy. RESULTS: Of 31,748 women with stage I to III breast cancer, 5,575 (18%) received chemotherapy. Chemotherapy was associated with younger age, fewer comorbidities, hormone receptor negativity, multiple primary tumors, and advanced disease. Patients who received chemotherapy were less likely than other patients to have pre-existing HD (45% v 55%, respectively; P < .001). The hazard ratios for CM, CHF, and HD for patients treated with doxorubicin (DOX) compared with patients who received no chemotherapy were 2.48 (95% CI, 2.10 to 2.93), 1.38 (95% CI, 1.25 to 1.52), and 1.35 (95% CI, 1.26 to 1.44), respectively. The relative risk of cardiotoxicity among patients who received DOX compared with untreated patients remained elevated 5 years after diagnosis. CONCLUSION: When baseline HD was taken into account, chemotherapy, especially with anthracyclines, was associated with a substantially increased risk of CM. As the number of long-term survivors grows, identifying and minimizing the late effects of treatment will become increasingly important. 相似文献
47.
Improvement in quality of cryopreserved human spermatozoa by swim-up before freezing 总被引:4,自引:0,他引:4
F. PÉREZ-SÉNCHEZ T. G. COOPER C. H. YEUNG E. NIESCHLAG 《International journal of andrology》1994,17(3):115-120
Selecting a population of spermatozoa by the swim-up technique yields, after freezing and thawing, a population of cells that contains proportionally more spermatozoa which are morphologically normal, fewer spermatozoa with damaged tail membranes, and a greater percentage of progressively motile spermatozoa with greater velocities and amplitudes of head displacement than those obtained after freezing and thawing the same semen samples in the normal way. This pattern was found for the semen from 10 patients and five volunteers. However, the cells selected by swim-up were as susceptible to the stresses caused by freezing and thawing as unselected spermatozoa in the original semen sample, and the improvement came from the better quality of the initial sample. 相似文献
48.
This article reviews the current status and controversies of the 3 commonly used antifibrinolytics-epsilon-aminocaproic acid, tranexamic acid and aprotinin-during liver transplantation. There is no general consensus on how, when or which antifibrinolytics should be used in liver transplantation. Although these drugs appear to reduce blood loss and decrease transfusion requirements during liver transplantation, their use is not supported uniformly in clinical trials. Aprotinin has been studied more extensively in clinical trials and appear to offer more advantages compared to two other antifibrinolytics. Because of the diverse population of liver transplant recipients and the potential adverse effects of antifibrinolytics, especially life-threatening thromboembolism, careful patient selection and close monitoring is prudent. Further studies addressing the risks and benefits of antifibrinolytics in the setting of liver transplantation are warranted. 相似文献
49.
Investigation of, the cause of low sperm motility in asthenozoospermic patients by multiple quantitative tests 总被引:1,自引:0,他引:1
C. H. YEUNG M. BALS-PRATSCH U. A. KNUTH E. NIESCHLAG 《International journal of andrology》1988,11(4):289-299
Multiple tests were done on the ejaculates of 10 asthenozoospermic patients and nine healthy normozoospermic volunteers in an attempt to identify individually the cause of low sperm motility in these patients. Possible defects in the sperm plasma membrane and the motility apparatus of sperm, and in epididymal function affecting the development of motility, were investigated. The presence of seminal sperm antibodies or any motility-inhibiting factors in the seminal plasma that could be removed by washing were also tested. Each test was positive in only one or two patients but axonemal dysfunction was identified in nine patients. Removal of seminal plasma from asthenozoospermic samples did not improve sperm motility to any greater extent than with donor ejaculates, and the motile sperm of these patients exhibited characteristics mostly similar to those of donors under various incubation conditions. Selection procedures are, therefore, required to obtain samples of good quality sperm from such asthenozoospermic ejaculates. 相似文献
50.
Amir-Reza Hosseinpour Shay Cullen Victor T Tsang 《European journal of cardio-thoracic surgery》2006,30(3):508-514
Heart transplantation is a recognised treatment for end-stage heart failure of any cause including congenital heart disease. Congenital heart disease has contributed relatively little to the adult heart transplant activities in the past two decades. However, this is likely to change as an increasing number of children with congenital heart disease reach adulthood because of the advances in paediatric cardiology and surgery. Some of these grown-ups with congenital heart disease (GUCH patients) will need transplantation for late myocardial dysfunction either secondary to uncorrected lesions, or despite previous repair or palliative surgery. These patients are managed along the same clinical principles as those with cardiac failure of other aetiologies, despite the lack of any evidence to support this approach. Nevertheless, they introduce new challenges. First, some may have pulmonary vascular disease and require heart-lung transplantation, or lung transplantation combined with repair of their cardiac defects. Second, those with failing Fontan circulation are usually much sicker than other transplant candidates, with protein-losing enteropathy along with renal and hepatic dysfunction. Third, a suitable donor organ may not be found due to elevated levels of antibodies in response to previous blood transfusions and possibly the previous implantation of homografts. Fourth, the operation may be technically difficult because of the presence of adhesions secondary to previous operations, collaterals, and unusual anatomy. Fifth, postoperative care may be complicated because of predisposition to bleeding, infection and pulmonary hypertension, and the presence of residual aortopulmonary collaterals resulting in a significant left-to-right shunt. Despite a higher early mortality, the overall results of heart transplantation so far have been encouraging with survivals similar to that of adults with acquired heart disease and that of the paediatric population. However, this may change as the proportion of high-risk patients (failing Fontans) increases. GUCH patients with Eisenmenger's syndrome may be offered lung transplantation with repair of the cardiac defect or heart-lung transplantation. However, because of the limited success of these approaches, and improved management of pulmonary hypertension, patient selection remains difficult. 相似文献