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   27608篇
  免费   1431篇
  国内免费   148篇
耳鼻咽喉   155篇
儿科学   657篇
妇产科学   457篇
基础医学   3534篇
口腔科学   768篇
临床医学   1825篇
内科学   7111篇
皮肤病学   476篇
神经病学   2351篇
特种医学   920篇
外科学   4487篇
综合类   165篇
一般理论   1篇
预防医学   752篇
眼科学   401篇
药学   1926篇
中国医学   64篇
肿瘤学   3137篇
  2022年   239篇
  2021年   495篇
  2020年   280篇
  2019年   357篇
  2018年   518篇
  2017年   370篇
  2016年   422篇
  2015年   502篇
  2014年   628篇
  2013年   760篇
  2012年   1229篇
  2011年   1367篇
  2010年   771篇
  2009年   676篇
  2008年   1172篇
  2007年   1380篇
  2006年   1312篇
  2005年   1408篇
  2004年   1330篇
  2003年   1269篇
  2002年   1325篇
  2001年   972篇
  2000年   954篇
  1999年   931篇
  1998年   393篇
  1997年   327篇
  1996年   358篇
  1995年   229篇
  1994年   204篇
  1993年   195篇
  1992年   564篇
  1991年   515篇
  1990年   539篇
  1989年   487篇
  1988年   462篇
  1987年   452篇
  1986年   405篇
  1985年   416篇
  1984年   303篇
  1983年   212篇
  1982年   125篇
  1979年   224篇
  1978年   153篇
  1977年   149篇
  1974年   135篇
  1971年   139篇
  1970年   135篇
  1969年   131篇
  1968年   141篇
  1967年   142篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
From 1965 to 1968, 7716 Japanese-American men were examined and tested for serum cholesterol. After 22 years, 1380 incident cancer cases were identified. Of the site-specific cancers, only colon cancer cases had a significantly lower mean serum cholesterol value than that of noncases (213.0 mg/dl vs 219.0 mg/dl). When the study subjects were separated into either a low, middle or high group, based on their serum cholesterol values, there was a significant inverse trend for cases of oral/pharyngeal/esophageal cancer combined. The association was present for cases diagnosed within 10 years of examination (p = 0.012), but not for cases diagnosed after 10 years. This suggests that the inverse association is due to the metabolic effects of undiagnosed oral/pharyngeal/esophageal cancer upon serum cholesterol levels. These results are discussed in relation to other studies on serum cholesterol.  相似文献   
92.
To examine the difference between response of nasal mucosa to specific antigen and that to non-specific stimulus in the same patient, specific nasal provocation was performed using the house dust antigen disk while nasal respiratory resistance was continuously measured by Rhinograph. On the other hand, non-specific nasal provocation was performed with inhalation of methacholine while nasal respiratory resistance was continuously measured with Astograph. Thereafter the resulting response curves were analyzed. Subjects were 12 males and 9 females, who had nasal obstruction, watery rhinorrhoea and sneeze, and were proved to have allergic rhinitis by house dust. To analyze specific response curve, primary nasal respiratory resistance (Rrs.N), reacting time (Ta) and slope signifying increase of nasal respiratory resistance (delta Rrs.N) were used as parameters. To analyze non-specific response curve, primary nasal respiratory resistance (Rrs.N.cont), minimum dose of methacholine that caused an increase of nasal respiratory resistance (Dmin.N) and slope signifying increase of nasal respiratory resistance (Sd.N) were used as parameters. Ta and Dmin.N reflect sensitivity of nasal mucosa. Their values become smaller, it means sensitivity of nasal mucosa becomes higher. Delta Rrs.N and Sd.N reflect reactivity of nasal mucosa. Their values become larger, it means reactivity of nasal mucosa becomes larger.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
93.
Growth of the patients with hematological malignancies, aplastic anemia, Fanconi's anemia, and Wiscott-Aldrich syndrome who had been treated with bone marrow transplantation (BMT) was studied. Fourteen out of 21 patients showed suppression of linear growth after BMT. Recovery of the growth velocity after 1-2 years tended to occur if BMT was performed at younger age. Six of eight patients with chronic graft-versus-host-disease (CGVHD) had impaired growth after BMT, whereas eight of 13 (61%) without CGVHD did. Provocative tests for growth hormone (GH) performed 5-72 months after BMT revealed three boys who showed poor response to more than two different stimuli. Two of these three boys had prolonged suppression of growth. Neither the age at BMT, difference in disease, nor presence of posttransplant growth retardation gave significant difference in the response of GH to provocative tests. It was concluded that approximately two-thirds of marrow-grafted children experienced transient decrease in growth velocity after BMT.  相似文献   
94.
A statistic analysis was carried out on the 4,956 inpatients admitted to our Department of Urology from April 1972 to December 1991. The patients included 3,399 males and 1,557 females. A total of 4,105 operations including 255 renal allotransplantations were performed on 3,590 patients. Open surgery for upper urinary tract stones has been replaced by extracorporeal shock-wave lithotripsy (ESWL) in the last three years.  相似文献   
95.
In embryology, a persistent connection of the left superior vena cava to the left atrium rarely coexists with a coronary sinus. We herein report an unusual case of persistent left superior vena cava terminating in a left atrium with normal coronary sinus, which was revealed at the time of permanent pacemaker implantation after a second operation for recurrent left atrioventricular valve regurgitation. Because this anomaly had gone undiagnosed at the first operation, we were unable to diagnose it prior to the second operation, because the preoperative coronary angiogram clearly demonstrated a coronary sinus that was not dilated. We would have repaired the anomaly using a patch or other procedure had it been diagnosed before the second operation in order to prevent cyanosis or brain complications secondary to right-to-left shunting. One should always be on guard for this rare condition.  相似文献   
96.
Coagulation system and platelets play an important role in the stage of lodgement of tumor cells. We examined abilities of human and hamster pancreatic cancer cell lines to aggregate platelets in vitro, and investigated the effect of prostaglandin E1, I2, on artificial liver metastases of pancreatic cancer in Syrian golden hamster. Platelet aggregating activities were found in five out of six human pancreatic cancer cell line and thromboplastin likes activity in five cell lines. Diisopropanolnitrosamine induced hamster pancreatic cancer cells (HPK-1) were able to aggregate platelets both in vitro and in vivo and these activities were inhibited by prostaglandin I2. Hamster was inoculated intraportally with 1 X 10(6) HPK-1 cells. After two weeks autopsy of these hamsters revealed multiple metastatic nodules on liver surface. In this model we administered prostaglandin E1, I2 into the portal vein five minutes before cell inoculation. Number of liver surface nodules were significantly decreased to 33.1 + 7.0, 11.0 + 9.6 in hamster given 100g PGE1 PGI2 before cell inoculation, compared with control group of hamsters (62.0 + 6.6 PH9.3, 66.1 + 13.9 PH7.4). But administration of prostaglandin after cell injection was not effective. In all cases none of extrahepatic metastases were noted. Inhibitory action of PGE1 PGI2 on liver metastasis is suspected to be related to inhibition of platelet aggregation.  相似文献   
97.
Summary Only one peptide of CD4 (amino acid residues 70–132) among 16 synthetic peptide fragments selectively inhibited HIV-1 replication and HIV-1-induced syncytium formation. Several smaller peptides within this region did not show any activity, except for the peptide (86–132) which showed somewhat lower activity.  相似文献   
98.
A new cell line (DMBA-OC-1) from 7,12-dimethylbenz (a) anthracene (DMBA) which induced ovarian carcinoma in rat was established and characterized. DMBA-OC-1 cells showed a paving-stone-like growth pattern at around the 10th to 20th passage, but at the point exceeding the 40th passage the cells showed a spindle form, having strong trends both towards flocculation and piling-up. Furthermore, diastase-resistant PAS-positive and hyaluronidase-digested Alcian blue positive substances were observed in cytoplasms. The cells also showed marked phagocytic activity. These findings suggest that DMBA-OC-1 cells are most likely the site of mesothelial cell origin.  相似文献   
99.
100.
Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP. Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA) analysis were performed upon clinical data, distribution of interictal spikes, and ictal chronology of seizures. From MVA, a final predictive model (FPM) was determined to better predict TPP and APP. Forty patients showed TPP (78.5%) and 11 patients APP (21.5%). Accuracy of ictal SPECT was higher in the unilateral (UIS) than in the bilateral (BIS) interictal spikes group (P = 0.05). FPM showed that patients exhibiting BIS, with shorter proportion of the electrographic seizure occurring after completion of tracer injection, and longer clinical than EEG seizure duration had more APP (P = 0.003). Generalized tonic-clonic seizures did not result in more APP. We concluded that analysis of ictal SPECT in TLE requires the knowledge of TPP and APP, the distribution of interictal spikes on temporal lobes and the ictal chronology of seizures. BIS showed that beyond a more complex epileptogenicity and seizure propagation, they may also lead to APP.  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