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   2511篇
  免费   304篇
  国内免费   22篇
耳鼻咽喉   79篇
儿科学   86篇
妇产科学   43篇
基础医学   195篇
口腔科学   104篇
临床医学   349篇
内科学   599篇
皮肤病学   44篇
神经病学   109篇
特种医学   317篇
外科学   244篇
综合类   26篇
预防医学   349篇
眼科学   79篇
药学   82篇
肿瘤学   132篇
  2023年   53篇
  2022年   27篇
  2021年   31篇
  2020年   54篇
  2019年   38篇
  2018年   70篇
  2017年   44篇
  2016年   64篇
  2015年   71篇
  2014年   118篇
  2013年   162篇
  2012年   79篇
  2011年   98篇
  2010年   85篇
  2009年   105篇
  2008年   95篇
  2007年   119篇
  2006年   100篇
  2005年   85篇
  2004年   73篇
  2003年   45篇
  2002年   57篇
  2001年   56篇
  2000年   50篇
  1999年   48篇
  1998年   75篇
  1997年   96篇
  1996年   84篇
  1995年   61篇
  1994年   66篇
  1993年   59篇
  1992年   29篇
  1991年   26篇
  1990年   44篇
  1989年   57篇
  1988年   43篇
  1987年   44篇
  1986年   50篇
  1985年   41篇
  1984年   20篇
  1983年   26篇
  1982年   31篇
  1981年   37篇
  1980年   21篇
  1979年   12篇
  1978年   12篇
  1977年   15篇
  1976年   20篇
  1975年   19篇
  1969年   4篇
排序方式: 共有2837条查询结果,搜索用时 15 毫秒
21.
Cholecystokinin-decreased food intake in rhesus monkeys   总被引:1,自引:0,他引:1  
  相似文献   
22.
The world's first deliveries of normal babies after use of flow cytometric separated human sperm cells (MicroSort) for preconception gender selection are reported. Offspring were of the desired female gender in 92.9% of the pregnancies. Most of these pregnancies and births were achieved after simple intrauterine insemination.   相似文献   
23.
Insemination with donor spermatozoa is an integral part of infertility treatment. For the last 3 years in our unit, intrauterine insemination with donor spermatozoa (IUID) has been used in preference to vaginal insemination. In this retrospective study, patients were offered an initial course of five single intrauterine inseminations with cryopreserved donor spermatozoa and treatment was then reviewed. A total of 389 patients received 1465 inseminations. In all, 1119 cycles were monitored using luteinizing hormone serum analyses and 346 cycles using the urine home test kits. The clinical pregnancy rate per insemination for the cycles monitored by the serum assay was 18.0% (202/1119) compared with the urine cycles (13.7%, 46/346) (P <05). The pregnancy loss rate was not significantly different (14.4%, 29/202 and 21.7%, 10/46) (serum and urine cycles respectively). The viable clinical pregnancy rate was significantly higher (P <03) for the serum cycles than for the cycles using the urinary monitoring (15.5%, 173/1119 and 10.4%, 36/346 respectively). The cycles monitored by serum assay had a significantly higher cumulative viable clinical pregnancy rate (P <0001) of 70.2% after nine inseminations compared with the urine monitored cycles of 54.8%. The majority of patients opted for the serum cycles, with a minority self-selecting the urine cycles mainly for travelling convenience. The explanation for the significant differences between the viable clinical pregnancy rates per insemination and the cumulative viable clinical pregnancy rates may be due to the sensitivity of the urine home test kit or the patients' interpretation of the result.   相似文献   
24.
25.
26.
Ultrasound scans of 51 consecutive patients with gallbladder wall thickening were reviewed, and specific sonographic features were correlated with surgical and clinical follow-up. Two patterns of thickening were identified as specific indicators of the presence or absence of acute cholecystitis. "Striated" wall thickening, consisting of several alternating, irregular, discontinuous, lucent and echogenic bands, was seen in eight of 13 patients (62%) with acute cholecystitis. This pattern was not encountered in any of the patients who did not have acute cholecystitis. Conversely, "three-layer" thickening, consisting of a single circumferential lucent zone between two relatively uniform echogenic layers, was seen in only one of 13 patients (8%) with acute cholecystitis but in 11 of 38 patients (29%) with other diagnoses. Other abnormalities, including the presence of intramural echogenic foci and wall irregularities, were more frequently seen in patients with acute cholecystitis but were not as helpful. Use of these features may suggest or help exclude a diagnosis of acute cholecystitis in those patients in whom the cause of gallbladder wall thickening is otherwise not apparent.  相似文献   
27.
The ERAS guidelines are intended to identify, disseminate and promote the implementation of the best, scientific evidence-based actions to decrease variability in clinical practice. The implementation of these practices in the global clinical process will promote better outcomes and the shortening of hospital and critical care unit stays, thereby resulting in a reduction in costs and in greater efficiency. After completing a systematic review at each of the points of the perioperative process in cardiac surgery, recommendations have been developed based on the best scientific evidence currently available with the consensus of the scientific societies involved.  相似文献   
28.
Advances in techniques of molecular biology have made possible the amplification of specific genes from single cells. This has a major clinical application in preimplantation diagnosis of monogenic disorders. However, the incidence of allele specific amplification failure (allele drop out) in heterozygous single cells can lead to misdiagnosis and the transfer of affected embryos. Few studies have been done to investigate the actual cause of allele drop out, although some investigators have succeeded in reducing but not eliminating it. Here we report the efficiency of amplifying both alleles in heterozygous cells lysed according to two different protocols. A total of 177 heterozygous cells from carriers of cystic fibrosis (CF) and haemoglobin C (HbC) were lysed using two different lysis buffers. Interestingly none of the cells that were lysed with sodium dodecyl sulphate/proteinase K showed any example of allele specific amplification failure whereas in those lysed by KOH/dithiothreitol it was present in 17.6 and 4.7% of the CF and HbC cells respectively. Our results suggest that the phenomenon of allele specific amplification failure is at least in part dependent on the lysis buffer used.   相似文献   
29.
Obstetrical sciatic palsy have been frequently seen in our hospital, but bibliography about this subject is rare, not only in Spanish but also in other languages. We review our experience about this pathology, and if it is possible, to contribute to prevent its occurrence.  相似文献   
30.
In a simulated field trial Bacillus thuringiensis var israelensis (BTI) pellet formulation exhibited an enhanced efficacy with increasing dose. A dosage of 1.0 and 1.5 ppm was most effective under simulated field conditions. In field trials persistence of BTI pellet (1.0 ppm) was observed for 35 days in moderately polluted water collection as compared to 21 days in highly polluted water bodies.KEY WORDS: Bacillus thuringiensis, Malaria, Mosquito control  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