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   7746篇
  免费   696篇
  国内免费   41篇
耳鼻咽喉   80篇
儿科学   191篇
妇产科学   235篇
基础医学   1122篇
口腔科学   158篇
临床医学   808篇
内科学   1275篇
皮肤病学   104篇
神经病学   513篇
特种医学   592篇
外科学   892篇
综合类   137篇
一般理论   3篇
预防医学   747篇
眼科学   220篇
药学   516篇
中国医学   4篇
肿瘤学   886篇
  2021年   105篇
  2020年   46篇
  2019年   108篇
  2018年   120篇
  2017年   95篇
  2016年   84篇
  2015年   110篇
  2014年   174篇
  2013年   227篇
  2012年   303篇
  2011年   314篇
  2010年   217篇
  2009年   174篇
  2008年   303篇
  2007年   325篇
  2006年   336篇
  2005年   294篇
  2004年   319篇
  2003年   322篇
  2002年   281篇
  2001年   257篇
  2000年   253篇
  1999年   267篇
  1998年   144篇
  1997年   148篇
  1996年   141篇
  1995年   106篇
  1994年   94篇
  1993年   92篇
  1992年   155篇
  1991年   181篇
  1990年   179篇
  1989年   180篇
  1988年   173篇
  1987年   172篇
  1986年   153篇
  1985年   185篇
  1984年   108篇
  1983年   103篇
  1982年   65篇
  1981年   65篇
  1980年   68篇
  1979年   91篇
  1978年   61篇
  1977年   67篇
  1976年   56篇
  1975年   63篇
  1974年   57篇
  1973年   67篇
  1972年   55篇
排序方式: 共有8483条查询结果,搜索用时 0 毫秒
21.
A 44-year-old man with right-sided herpes zoster ophthalmicus (HZO) developed ipsilateral third and sixth cranial nerve palsies and first-division trigeminal (fifth cranial nerve) sensory loss. MRI revealed contrast enhancement of the cisternal and cavernous portions of the third cranial nerve and high signal on a FLAIR sequence within the ipsilateral medulla at the presumed location of the trigeminal nucleus and tract. To our knowledge, this is the first report of the combination of these imaging findings in HZO.  相似文献   
22.
Growth/differentiation factor 5 enhances chondrocyte maturation.   总被引:8,自引:0,他引:8  
Growth/differentiation factor 5 (GDF5) is required for limb mesenchymal cell condensation and joint formation during skeletogenesis. Here, we use a model consisting of long-term, high-density cultures of chick embryonic limb mesenchymal cells, which undergo the entire life history of chondrocyte development, to examine the effects of GDF5 overexpression on chondrocyte maturation. Exposure to GDF5 significantly enhanced chondrocyte hypertrophy and maturation, as determined by the presence of alkaline phosphatase activity, collagen type X protein production, and the presence of a sulfated proteoglycan-rich extracellular matrix. Histologic analysis also revealed an increase in cell volume and cellular encasement in larger lacunae in GDF5-treated cultures. Taken together, these results support a role for GDF5 in influencing chondrocyte maturation and the induction of hypertrophy in the late stages of embryonic cartilage development, and provide additional mechanistic insights into the role of GDF5 in skeletal development.  相似文献   
23.
24.
25.
26.
27.
28.
29.
OBJECTIVE. Our objective was to study the imaging findings in patients who had gastric and duodenal obstruction as a long-term complication of cholangiocarcinoma and to determine if the obstruction was associated with radiation therapy. MATERIALS AND METHODS. Between 1973 and 1989, 96 patients had either curative resection or palliative stenting for cholangiocarcinoma involving the hepatic duct bifurcation. Sixty-three (66%) also received adjuvant radiation therapy ranging from 4960 to 7220 rad (cGy). Gastric outlet or duodenal obstruction or both developed subsequently in seven of the 63 patients treated with radiation therapy. Radiographic studies, including upper gastrointestinal series and CT, and medical and surgical records for these seven patients were retrospectively reviewed. RESULTS. Upper gastrointestinal series in the seven patients with obstruction showed narrowing of the lumen, deformity and enlargement of gastric and duodenal mucosal folds, and delayed gastric emptying. CT performed in five of the seven patients showed thickening of the wall of the gastric antrum and small bowel and retained food and fluid within the stomach. All seven patients required gastrojejunostomy; at surgery, dense adhesions and fibrosis were found, and it was not evident whether the obstruction was due to the tumor or to radiation fibrosis. However, because this complication was seen only after radiotherapy, it was presumed to be radiation fibrosis. CONCLUSION. Our experience suggests that radiation therapy increases the risk of postoperative gastric and duodenal obstruction in patients undergoing surgery for cholangiocarcinoma.  相似文献   
30.
Fat absorption from two different premature infant formulas and one full-term formula containing three different fat blends was investigated in two groups of premature infants. The first group of nine infants (gestational age, 29.1 +/- 0.88 weeks; postnatal age, 3.13 +/- 0.71 weeks) was fed alternately for 1 week each SMA preterm formula containing either high levels (50%) of medium-chain triglycerides (MCT) (6:0, 8:0, and 10:0) or high levels (86%) of long-chain triglycerides (LCT) (greater than or equal to C12). Except for fat blends, the formulas were otherwise identical. The second group of 11 infants (gestational age, 30.5 +/- 0.77 weeks, studied at a postnatal age of 4.33 +/- 0.91 weeks) was fed for 1 week a full-term infant formula, S-26, containing 98% LCT. Fat absorption (studied during a 3-day fat balance period) was similar irrespective of fat blend: 89.08 +/- 2.37% during feeding of preterm SMA, 50% MCT; 87.0 +/- 3.81% during feeding of preterm SMA, 86% LCT; and 83.00 +/- 2.89% during feeding of S-26, 98% LCT. Weight gain (grams per day) and increase in length (centimeters per day) were 23.2 +/- 1.7, 21.20 +/- 1.7, and 14.28 +/- 2.9, and 0.17 +/- 0.06, 0.16 +/- 0.04, and 0.22 +/- 0.07 during feeding of the three fat blends, respectively. Lipase activity levels in fasting gastric aspirates were higher during feeding of the LCT than the MCT formula. The possible stimulation of gastric lipase secretion secondary to long-chain fatty acid stimulation of cholecystokinin secretion might be related to the efficient digestion of formula fat, irrespective of triglyceride-fatty acid chain length.(ABSTRACT TRUNCATED AT 250 WORDS)  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