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   11326篇
  免费   384篇
  国内免费   77篇
耳鼻咽喉   49篇
儿科学   402篇
妇产科学   252篇
基础医学   751篇
口腔科学   177篇
临床医学   747篇
内科学   2728篇
皮肤病学   173篇
神经病学   543篇
特种医学   212篇
外科学   1596篇
综合类   852篇
一般理论   5篇
预防医学   1781篇
眼科学   214篇
药学   804篇
  7篇
中国医学   250篇
肿瘤学   244篇
  2023年   111篇
  2022年   229篇
  2021年   336篇
  2020年   320篇
  2019年   762篇
  2018年   647篇
  2017年   392篇
  2016年   209篇
  2015年   230篇
  2014年   449篇
  2013年   452篇
  2012年   390篇
  2011年   424篇
  2010年   333篇
  2009年   326篇
  2008年   310篇
  2007年   303篇
  2006年   248篇
  2005年   182篇
  2004年   112篇
  2003年   122篇
  2002年   89篇
  2001年   97篇
  2000年   95篇
  1999年   61篇
  1998年   57篇
  1997年   43篇
  1996年   42篇
  1995年   38篇
  1994年   40篇
  1993年   41篇
  1992年   27篇
  1991年   28篇
  1989年   17篇
  1988年   23篇
  1987年   19篇
  1986年   17篇
  1985年   285篇
  1984年   483篇
  1983年   401篇
  1982年   400篇
  1981年   340篇
  1980年   316篇
  1979年   390篇
  1978年   283篇
  1977年   195篇
  1976年   283篇
  1975年   249篇
  1974年   255篇
  1973年   243篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
A family history study of second-degree relatives of 19 patients with anxiety neurosis (panic disorder) and 19 controls showed a morbidity risk of 9.5% among the former compared with 1.4% among the latter. These risks were approximately half those found among first-degree relatives. Female relatives were at higher risk for anxiety neurosis. The risk for other psychiatric illnesses did not differ between the relatives of anxiety neurosis and controls.  相似文献   
12.
13.
Growth of diploid cells from breast cancers   总被引:1,自引:0,他引:1  
Cell cultures were derived from normal and cancerous breast tissues and from metastases by methods that selected for relatively adherent epithelial aggregates. Karyotypic analyses of first or second passage cultures yielded predominantly normal diploid cells. Nonclonal aberrations were more common in tumor-derived than in normal cultures. Three of the cultures that originated from metastases were characterized by abnormal clones. These results support observations based on DNA content, which indicate that a considerable fraction of breast cancers are composed predominantly of diploid cells. They differ greatly from chromosomal findings in long-term cultures of tumor effusions and thus emphasize the karyotypic diversity that can be found in tumors from a single tissue of origin--the breast.  相似文献   
14.
The effect of adrenergic and cholinergic drugs on short incubation “active” E rosette formation was studied in 19 patients with bronchial asthma and 17 healthy controls. Both groups had an equal absolute number of baseline “active” E rosettes, but the asthmatics demonstrated a higher percent baseline value. The beta adrenergic drug isoproterenol (10?3 M) inhibited the formation of “active” E rosettes in asthmatics by only 18.0% as compared to a 60.8% inhibition in the control group. Carbamylcholine (10?5 M) a cholinergic agonist, also showed a lower than normal response in asthmatics, 34.3% enhancement of “active” E rosetting compared to a 52.4% enhancement in the controls. The alpha adrenergic agent phenylephrine (10?5 M) exhibited equal enhancing effects in both groups, 34.2% in the asthmatics and 36.5% in the controls. Isoproterenol (10?3 M) had a minimal effect on inhibition of long incubation “total” E rosettes in both groups studied. The beta adrenergic abnormality conforms to the beta blockade theory of asthma of Szentivanyi. The cholinergic abnormality is unexplained in view of the hyperresponsiveness of patients with asthma to cholinergic agents in vivo. Patients with bronchial asthma probably have an autonomic dysfunction that may play a role in the pathogenesis of their disease.  相似文献   
15.
Hamsters in deep experimentally induced hypothermia, at body temperatures between 7 degrees C and 11.5 degrees C, were microinjected with 5-HT and ACh at brain sites in the anterior-preoptic area of the hypothalamus (AH/POA). ACh or 5-HT was injected into an AH/POA site at different starting core temperatures in different groups of hypothermic hamsters. Colonic temperatures (Tc) were maintained, following He-Cold induction, in a temperature controlled environmental chamber and measured with a YSI thermister probe and YSI telethermometer. Injections of either 5-HT or ACh at Tc's between 7.0 degrees C and 9.0 degrees C elicited only modest increases in Tc i.e., 0.3 degrees C--0.6 degrees C, respectively. As Tc increased, however, to ranges between 9.1 degrees C--10.0 degrees C and in different animals to greater than 10 degrees C both ACh and 5-HT at the same sites elicited significant increases in Tc, 1.5 degrees C for 5-HT and 2.2 degrees C for ACh compared to saline injections. These data suggest that at the lowest Tc's we are observing a "cold block" of temperature sensitive sites in the AH/POA. Increasing the starting Tc beyond 9.0 degrees C however, evokes significant increases in heat-gain following AH/POA injection of either ACh or 5-HT. These data are consistent with Myers' observations concerning the organization of heat-gain mechanisms at AH/POA sites. In addition, they suggest that both the afferent limb of the heat-gain circuit (5-HT) and the efferent limb of the circuit (ACh) are functionally impaired when Tc is close to the physiological limit in the He-Cold hypothermic hamster.  相似文献   
16.
In response to the spiraling anger and frustration voiced by the emergency room (ER) medical staff and the observed negative interactions between the alcohol-dependent patient and the ER staff, the author completed a 6-month retrospective review of all patients evaluated by the ER service with a complaint of alcohol abuse, chronic alcoholism, or requesting detoxification. As a result of that study, an ER-based comprehensive approach to the management of this population was proposed. Utilizing an existing Connecticut state statute, a specific approach to manage the skid-row alcoholic arriving repeatedly in the ER was developed. I report on this ER-based model and an approach to "capturing" the skid-row alcoholic.  相似文献   
17.
18.
There are perhaps five strategies either presently advocated or under investigation for prevention of recurrent urinary tract infection (UTI): antibiotics, including natural peptides; functional foods; vaccines; probiotics; and miscellaneous, including avoidance of spermicides and maintenance of good hygiene. It is not possible to state the proportion of patients using antibiotics versus foods such as cranberry or using alternative approaches such as avoidance of spermicides. The majority of women who are referred to specialists will be prescribed long-term, low-dose antibiotics. However, given the magnitude of the problem, it is safe to state that large numbers of women are at least experimenting with alternative remedies such as drinking of cranberry juice or ingestion of herbal remedies with a view to enhancing their immune response. Vaccine development remains a long way from human use and has yet to be developed for organisms other than Escherichia coli. The use of probiotics to restore the normal vaginal flora and provide a competitive bacterial barrier to pathogens is close to becoming available as an alternative preventive approach. The next decade should see the introduction of new methods for reduction of the high incidence of UTI and better management of recurring urogenital infections.  相似文献   
19.
BACKGROUND: To describe the ultrasound biomicroscopic (UBM) features of anterior segment cysts. DESIGN: A retrospective case series. PARTICIPANTS: One hundred eighteen eyes with anterior segment cysts examined by UBM at The New York Eye and Ear Infirmary between August 1992 and November 1997 were included in this study. INTERVENTION: The authors reviewed demographic and diagnostic data from the medical record including ocular and medical history, age, race, gender, and intraocular pressure. Ultrasound data concerning the type, number, position, and acoustic characteristics of cysts were recorded. The authors then correlated the written, clinical, and UBM characteristics. RESULTS: One hundred eyes (92.6%) had neuroepithelial cysts. Ninety (83.3%) of these had primary neuroepithelial cysts, 10 (9.3%) had cysts associated with uveitis, 7 (6.5%) had implantation cysts, and 1 (0.9%) had a cavitated ciliary body tumor. Neuroepithelial cysts typically were round or ovoid, thin-walled, and echolucent. Of the 90 eyes with primary neuroepithelial cysts, 56 (62.2%) had 3 or fewer cysts; multiple cysts (>3 per eye) were found in 34 eyes (37.8%). The multiple cysts occupied more than 180 degrees in 12 patients (13.3%). Primary neuroepithelial cysts were located at the iridociliary junction (74.2%), pars plicata (14.0%), pars plana (6.8%), and iris (5.0%). Implantation cysts (seven eyes) tended to have thicker walls and two contained a copious, echogenic material. CONCLUSION: The UBM results provide important information regarding location and extent of anterior segment cystic lesions. Ultrasound characteristics may help differentiate between neuroepithelial, implantation, and neoplastic cysts.  相似文献   
20.
In four patients with the nephrotic syndrome, renal biopsy revealed focal segmental membranous glomerulonephropathy (FSMGN) associated with the histologic patterns of "nil" disease (two cases), hereditary nephritis and diffuse diabetic glomerulosclerosis. The occurrence of FSMGN in association with other glomerular diseases, presumably unrelated to immune complex deposition, is infrequent in our experience. Rather than necessarily representing an early stage or milder form of membranous glomerulonephropathy, it may be an epiphenomenon. This interpretation has prognostic and therapeutic implications and raises important pathogenetic questions. In particular, this study suggests that in some instances, preexisting functional and structural abnormalities may play a role either in the deposition of preformed circulating immune complexes or in the local formation of immune complexes.  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