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   65747篇
  免费   4122篇
  国内免费   1710篇
耳鼻咽喉   857篇
儿科学   1203篇
妇产科学   2219篇
基础医学   8134篇
口腔科学   1181篇
临床医学   6986篇
内科学   12172篇
皮肤病学   1196篇
神经病学   4017篇
特种医学   2670篇
外国民族医学   6篇
外科学   8614篇
综合类   4269篇
现状与发展   7篇
一般理论   11篇
预防医学   3550篇
眼科学   1419篇
药学   5414篇
  37篇
中国医学   1730篇
肿瘤学   5887篇
  2024年   442篇
  2023年   667篇
  2022年   1370篇
  2021年   2216篇
  2020年   1451篇
  2019年   1766篇
  2018年   2023篇
  2017年   1529篇
  2016年   1583篇
  2015年   2343篇
  2014年   2924篇
  2013年   3408篇
  2012年   4817篇
  2011年   4690篇
  2010年   2992篇
  2009年   2622篇
  2008年   3543篇
  2007年   3555篇
  2006年   3386篇
  2005年   3131篇
  2004年   2830篇
  2003年   2706篇
  2002年   2354篇
  2001年   1845篇
  2000年   1612篇
  1999年   1343篇
  1998年   570篇
  1997年   470篇
  1996年   434篇
  1995年   395篇
  1994年   362篇
  1993年   264篇
  1992年   715篇
  1991年   589篇
  1990年   539篇
  1989年   494篇
  1988年   429篇
  1987年   427篇
  1986年   358篇
  1985年   302篇
  1984年   233篇
  1983年   194篇
  1982年   118篇
  1981年   125篇
  1980年   101篇
  1979年   208篇
  1978年   161篇
  1977年   103篇
  1976年   112篇
  1975年   102篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
A variety of approaches to quantify biomass in biofilms without disruption due to detachment have been developed over the years. One basic approach is the combination of advanced microscopy with molecular staining. However, many stains (e.g. 4',6-diamino-2-phenylindole, acridine orange or live-dead stains) can be non-specific when corrosion products, precipitates, and pipe material are present. In addition, some pipe materials cause high background when using epifluorescent microscopy. The new refinement discussed in this presentation used fluorescence spectroscopy to obtain the spectra from four common distribution system pipe materials: PVC, 'concrete' lined cast iron, cast iron, and galvanized steel. The emission maximum for all four materials was between 500 and 550 nm, but emissions radically decreased around 575-600 nm. A molecular probe, BO-PRO-3 (Molecular Probes, Inc., Eugene, OR, USA) was identified which has an emission intensity maximum at 599 nm (red), with emission intensity 200 times greater when it is bound to DNA. The BO-PRO-3 has greatly reduced non-specific staining and background problems. In the preliminary experiment, using diluted waste water, a significant exponential relationship was found between stained surface area/total area ratio and fixed biofilm inventory measurements from scraping heterotrophic plate counts (SHPC) on R2A medium. In addition, the biofilm inventory on different pipe material coupons from pilot distribution systems was also correlated to the stained surface area fraction and SHPC.  相似文献   
103.
104.
Inadvertent retention of surgical gauze during an operation can have disastrous consequences for both the patient and the surgeon. Several cases have been reported, particularly after abdominal surgery. However, it has never to our knowledge been reported as a leading cause of dysfunction of the Eustachian tube after orthognathic surgery. We recently encountered a patient in whom it presented with unilateral otitis media with an effusion after orthognathic surgery. All surgeons involved with orthognathic surgery should be aware that remnants of surgical gauze after orthognathic surgery can compromise the Eustachian tube and cause otitis media with an effusion.  相似文献   
105.
106.
We sought to determine the relationship between the mechanical axis-derived and the anatomic landmark-derived femoral rotational axes using three dimensional computed tomographic images of 20 lower extremities. The mechanical axis-derived femoral rotational axis was created on the distal articular surface of the femur using coronal mechanical limb axis and the reconstructed images of the femur. Then, we measured the angular difference between mechanical axis-derived and anatomic landmark-derived femoral rotational axes. The mechanical axis-derived femoral rotational axis was externally rotated with a mean of 2.2° (range, 0 to 4.7°; SD, 1.0) compared with the surgical epicondylar axis. Our findings should be considered to obtain a proper femoral rotational axis in total knee arthroplasty.  相似文献   
107.
108.
109.
110.

Introduction and hypothesis

To examine the effect of acute urinary retention (AUR) on the urodynamic function and molecular structure of rat bladders in pregnancy and after parturition.

Methods

Forty-eight nulliparous rats were distributed into AUR and non-AUR groups. AUR was induced by clamping the distal urethra of each rat after infusing 3 ml of saline for 60 min. Plasma progesterone levels and cystometric data were evaluated on the 14th day of gestation, 3 and 10 days postpartum, and in virgin rats. The immunoreactivity of caveolins and nerve growth factor (NGF) was analyzed. The number of caveolae in bladder muscle cells was evaluated by electron microscopy.

Results

Progesterone levels significantly increased during pregnancy and 3 days postpartum. In cystometric results, the AUR group has significantly shorter intercontraction interval, lower void volume and greater residual volume compared with the non-AUR. AUR rats exhibited higher NGF immunoreactivity, lower caveolin-1 immunoreactivity, and less caveolae in the bladder compared with the non-AUR. The caveolin-1 and NGF immunoreactivity and the number of caveolae in the bladder decreased during pregnancy and 3 days postpartum compared with virgin rats. By using Pearson correlations, we found significant correlations between urodynamic variables (residual volumes and intercontraction intervals) and the expressions of caveolin-1, caveolae and NGF in the AUR rats on the 14th day of gestation and 3 days postpartum.

Conclusions

Bladder dysfunction in pregnancy and immediately postpartum in a rat model caused by AUR is associated with the plasma progesterone level change and the expressions of caveolin, caveolae, and NGF in bladder muscle cells.  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