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   498336篇
  免费   35670篇
  国内免费   9168篇
耳鼻咽喉   6285篇
儿科学   10061篇
妇产科学   12700篇
基础医学   65443篇
口腔科学   14242篇
临床医学   45235篇
内科学   96431篇
皮肤病学   9996篇
神经病学   33132篇
特种医学   17873篇
外国民族医学   122篇
外科学   72893篇
综合类   28829篇
现状与发展   21篇
一般理论   81篇
预防医学   26221篇
眼科学   12721篇
药学   43720篇
  115篇
中国医学   8590篇
肿瘤学   38463篇
  2022年   3844篇
  2021年   7895篇
  2020年   5576篇
  2019年   6282篇
  2018年   8293篇
  2017年   6975篇
  2016年   6698篇
  2015年   9075篇
  2014年   12189篇
  2013年   14086篇
  2012年   19829篇
  2011年   20759篇
  2010年   13490篇
  2009年   11812篇
  2008年   17023篇
  2007年   17760篇
  2006年   17306篇
  2005年   15767篇
  2004年   13434篇
  2003年   12741篇
  2002年   11674篇
  2001年   30631篇
  2000年   30935篇
  1999年   25770篇
  1998年   6367篇
  1997年   5373篇
  1996年   4738篇
  1995年   4360篇
  1994年   3947篇
  1993年   3308篇
  1992年   16720篇
  1991年   15403篇
  1990年   14658篇
  1989年   14363篇
  1988年   12951篇
  1987年   12380篇
  1986年   11361篇
  1985年   10517篇
  1984年   7051篇
  1983年   5733篇
  1982年   2796篇
  1979年   5593篇
  1978年   3434篇
  1977年   3035篇
  1975年   2666篇
  1974年   3142篇
  1973年   2919篇
  1972年   2893篇
  1971年   2809篇
  1969年   2577篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
971.
We have developed an immunoadsorbent (IA) for ex vivo removal of IgE after in vitro screening of matrix (Sepharose and tresyl-activated Toyopearl) and ligand (monospecific rabbit polyclonal anti-IgE antiserum and monoclonal antibodies (Abs) or their Fab fragments). Specific adsorptive capacity (SAC) for IgE was maximal in Sepharose-based IA with both types of Abs. Fab-containing IA on Sepharose retained 70-90% of the SAC of native Ab-containing IA. Toyopearl-based IA showed comparable SAC under static conditions but worked unsatisfactorily under continuous flow conditions. To assess the complement-activating capacity (CAC) of IA in vitro anaphylatoxin (C3a, C4a, C5a) generation was applied. CAC was directly related with the amount of immobilized Ab ligand, without depending on Ab specific activity. Fab-containing IA showed more CAC than native Ab-containing IA, and polyclonal IA more than monoclonal IA. Therefore, IA for IgE apheresis were prepared from native monoclonal Abs and CNBr-activated Sepharose CL 4B under aseptic conditions and packed into a glass column. This IA was used in 17 clinical IgE apheresis treatments of five atopic asthma patients. No substantial side effects were observed; in vivo IA effectively removed IgE from plasma (83 to 98%).  相似文献   
972.
A case of a parathyroid cyst associated with an adenoma in a different gland is reported. A 55-year-old female was explored with preoperative diagnosis of primary hyperparathyroidism after endoscopic removal of a right ureteral stone. The operation revealed a cyst, 20 x 10 mm in size at the left lower gland, and a solid tumor, 32 x 12 x 7 mm in size and 1,300 mg in weight in the left upper gland. Histological examination disclosed a parathyroid cyst and an oxyphilic and chief cell adenoma, respectively. Postoperative course was uneventful including normalized serum Ca level. To our knowledge, 59 cases of parathyroid cysts have been reported in the Japanese literature, of which 31 were in the hyperparathyroid status. The most common causes were cystic degeneration of the adenomas. A parathyroid cyst with a concomitant adenoma in a different gland like our case is very rare. This is the first reported case in Japan and the sixth reported case in the world literature.  相似文献   
973.
A 34-year-old woman was admitted with an abnormal shadow on a chest X-ray film. Under a preoperative diagnosis of benign bronchogenic cyst, operation was carried out and the tumor was found to be originating from the right main vagal nerve in the mid-superior mediastinum. The vagal nerve was transected to remove the tumor. Pathological diagnosis was a neurinoma. Postoperative complication was chylothorax which was successfully treated with thoracic drainage and intravenous hyperalimentation.  相似文献   
974.
Serum level of sex hormone-binding globulin (SHBG) was measured by immunoradiometric assay in fifty two breast cancer patients and twenty nine healthy female volunteers. The results are as follows: 1) Although the serum SHBG concentration showed no significant difference between the breast cancer group and the healthy control group, the serum SHBG concentration in postmenopause was significantly higher in the breast cancer group (63.8 +/- 31.2nmol/ml/ml; mean +/- S.D.) than in the healthy control group (40.1 +/- 15.4nmol/ml). 2) Subsequently in the postmenopausal breast cancer group, the serum SHBG concentration was significantly higher in the estrogen receptor (ER)-negative cancer group (97.8 +/- 12.7nmol/ml) than in the ER-positive cancer group (55.8 +/- 32.1nol/ml). 3) No significant relationships were showed between the serum SHBG concentration and obesity or serum estradiol concentration in postmenopausal patients. 4) The serum SHBG concentration showed significant decrease 3 months after radical operation for breast cancer in postmenopausal patients. These results suggest the possibility of the SHBG synthesis in breast cancer tissue.  相似文献   
975.
We studied subsets and cytotoxicity of recombinant interleukin-2 (rIL-2) expanded tumor infiltrating lymphocytes (TIL) from renal cell cancer (RCC) patients. TIL were successfully expanded in 13 of 14 RCC cases using anti-CD3 during initial 48 hours of culture. Percentages of CD8 positive cells among rIL-2 expanded TIL at 1 tp 4 week(s) of culture were 56.2 +/- 15.1% (range 26.2 to 79.8%, N = 13) and not necessarily predominant over CD4 positive cells. NK and LAK activities of TIL at 3 to 6 weeks of culture were 31.6 +/- 15.8% (range 1.4 to 57.4%, N = 9) and 16.6 +/- 11.6% (range 3.8 to 35.6%, N = 6), respectively. Autologous and allogeneic RCC cytotoxicity of TIL at 3 to 4 weeks of culture were 17.9 +/- 19.7% (range 0 to 47.6%, N = 4) and 18.9 +/- 14.8% (range 0 to 47.3%, N = 12), respectively. Since there was no statistical difference between them, autologous specific cytotoxicity was not demonstrated. From these results of present study, it is unlikely that most of effector cells of rIL-2 expanded TIL in autologous RCC lysis are major histocompatibility complex restricted cytotoxic T cells. And we concluded that it is doubtful that TIL is significantly superior over LAK cells in immunotherapy of human RCC.  相似文献   
976.
Transrectal ultrasonotomography is useful in following patients with benign prostatic hypertrophy, because prostatic shape and weight are precisely assumed. We studied the effect of chlormadinone acetate (CMA) on benign prostatic hypertrophy. CMA (50 mg/day) was administered to 30 patients with benign prostatic hypertrophy. Weight reduction over 10% of the gland was noticed in 24 cases (80%). Mictional conditions were improved in 70% subjectively and in 71.4% objectively. However, the number of nocturia decreased in only 18.9%. Reduction rate of the weight was unrelated with the weight of prostate before administration of CMA. Duration of administration of CMA and the reduction rate were estimated. There was no definite difference in reduction rate for the first 15 months, but there was a slightly high reduction rate after administration of CMA for more than 24 months. In 3 cases, the shape and weight of prostate were studied after discontinuation of CMA. The size of prostate showed a tendency to increase gradually.  相似文献   
977.
O-beta-D-Galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)-D- glucopyranose (designated as 4'GL) is produced from lactose by Cryptococcus laurentii. The influence of chronic ingestion of 4'GL on body weight gain, organ weight, serum lipids, and liver lipids was investigated in rats. The body weight gains of the 5% and 10% 4'GL-diet groups were higher than that of the control group. Food intake and fecal dry weight were significantly increased (p less than 0.05) by 4'GL feeding. The 4'GL diet produced a significant increase (p less than 0.01) in the wet weight and contents of both the cecum and the colon. However, no significant increase was observed in the weight of the stomach, small intestine, liver, or other organs. The effects of 4'GL on serum and liver lipid levels were not observed in this experiment. The digestion of 4'GL was measured in vitro using the artificial gastric juice, alpha-amylase of human saliva, alpha-amylase of hog pancreas, and mucosa of rat intestine. 4'GL was not hydrolyzed by these enzymes. Long-term ingestion of 4'GL did not cause any induction of 4'GL hydrolyzing enzyme activity in the rat small intestine.  相似文献   
978.
979.
Clinically significant contact lens induced corneal warpage is seen in a small proportion of soft and rigid contact lens wearers. Previous studies using the keratometer have found no correlation between the fit of the lens and the induced topographic changes. In this study, using computer-assisted topographic analysis, seven eyes (four patients) with rigid contact lens-induced corneal warpage were noted to have topographic abnormalities that correlated with the decentered resting position of the contact lens on the cornea. The warpage topography for each of these corneas was characterized by a relative flattening of the cornea underlying the resting position of the contact lens. Lenses that rode high, for example, produced flattening superiorly and resulted in a relatively steeper contour inferiorly that simulated the topography of early keratoconus patients who had not worn contact lenses. After discontinuing contact lenses the corneal topography returned to a normal pattern in five eyes. Two eyes retained asymmetry that is not characteristic of normal corneas. Up to 6 months was required for the corneas to return to a stable topography after contact lens wear was discontinued.  相似文献   
980.
DNA synthesis in urothelial cells was determined 2, 4, 6, 10, and 16 weeks following dietary administration of promoters of bladder tumors to weanling male F344 rats. The experimental groups were fed AIN-76A diet or this diet containing 0.15% sodium phenobarbital, 3% uracil, 5% sodium saccharin, 2% sodium bicarbonate, or a combination of 5% sodium saccharin and 2% sodium bicarbonate. Two other groups were given Wayne rodent chow alone or in combination with 5% sodium saccharin. A group of rats given a drinking water containing 0.01% N-butyl-N-(4-hydroxybutyl)nitrosamine served as a positive control. With the exception of phenobarbital which increased the labeling index but did not induce hyperplasia, all other compounds increased the labeling index and induced hyperplasia. The combination of sodium saccharin and sodium bicarbonate was more effective than either compound alone in increasing the labeling index. Sodium saccharin was equally active when incorporated in either the AIN diet or the Wayne rodent chow. The present results suggest that a fundamental mechanism of bladder tumor promotion may be due to an increased DNA synthesis which leads to an increased turnover rate of urothelial cells rather than hyperplasia. However, since sodium saccharin is a promoter when incorporated into the Wayne diet but not into the AIN diet, the ability to stimulate DNA synthesis may be an important but insufficient condition for promotion by saccharin.  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