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   18329篇
  免费   1567篇
  国内免费   40篇
耳鼻咽喉   155篇
儿科学   518篇
妇产科学   516篇
基础医学   2531篇
口腔科学   605篇
临床医学   2126篇
内科学   3295篇
皮肤病学   429篇
神经病学   1707篇
特种医学   911篇
外科学   2322篇
综合类   484篇
一般理论   17篇
预防医学   2000篇
眼科学   228篇
药学   1143篇
  1篇
中国医学   18篇
肿瘤学   930篇
  2022年   141篇
  2021年   265篇
  2020年   202篇
  2019年   310篇
  2018年   358篇
  2017年   273篇
  2016年   264篇
  2015年   300篇
  2014年   422篇
  2013年   634篇
  2012年   838篇
  2011年   835篇
  2010年   544篇
  2009年   484篇
  2008年   717篇
  2007年   752篇
  2006年   693篇
  2005年   705篇
  2004年   698篇
  2003年   671篇
  2002年   647篇
  2001年   612篇
  2000年   672篇
  1999年   569篇
  1998年   272篇
  1997年   225篇
  1996年   257篇
  1995年   198篇
  1994年   177篇
  1993年   174篇
  1992年   440篇
  1991年   409篇
  1990年   410篇
  1989年   386篇
  1988年   330篇
  1987年   346篇
  1986年   302篇
  1985年   308篇
  1984年   285篇
  1983年   240篇
  1982年   143篇
  1980年   143篇
  1979年   200篇
  1978年   152篇
  1976年   132篇
  1975年   144篇
  1974年   143篇
  1973年   145篇
  1972年   149篇
  1971年   116篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
OBJECTIVE: Having demonstrated that dementia of acute onset represents a distinct syndrome with distinct outcomes, the authors investigated whether similar attributes describe cognitive impairment of acute onset (CIAO). METHODS: The authors conducted a secondary analysis of the Consortium to Investigate Vascular Impairment of Cognition study. RESULTS: Ninety patients met our criteria for CIAO. Compared with cognitive impairment of gradual onset, CIAO was associated with vascular features (odds ratio [OR]: 12.3, 95% confidence interval [CI]: 3.2-47.9), dementias other than Alzheimer disease (OR: 6.5, 95% CI: 2.1-20.8), and decreased survival (hazard ratio: 2.8, 95% CI: 1.6-4.6). CONCLUSIONS: Patients with CIAO are clinically identifiable and have distinct outcomes.  相似文献   
82.
A 74 year old man with light-chain myeloma developed amyloidosis with macroglossia after 10 years of therapy with alkylating agents. Over a 2-year period his tongue enlarged to persistently protrude from his mouth, inhibit his speech, interfere with normal swallowing and eventually threaten his airway. As a life-saving procedure the tumorous anterior two-thirds of the tongue was resected, with excellent primary healing. Within two weeks the patient's speech became comprehensible and his ability to eat returned to normal. Although rare in amyloidosis, massive macroglossia may occur and surgical correction is easily achieved.  相似文献   
83.
A case of surrogate pregnancy is described in the sister of a 40-year-old hysterectomized woman where two oocytes of the latter were fertilized in vitro with known donor sperm and transferred into the surrogate. A normal singleton pregnancy developed which was complicated after 24 weeks of gestation with recurrent antepartum hemorrhages due to grade 3 placenta praevia. A healthy female baby was delivered by elective cesarean section at 36 weeks of gestation. The legal, social, psychological, and ethical issues of surrogacy remain unsettled and are discussed in this case report.  相似文献   
84.
The authors conducted a complete audit of results of 38,633 mammographic examinations performed by 12 general radiologists during a 2-year period with a computerized reporting system. During this period, 11 group members attended 17 dedicated mammography courses. Audit results were analyzed for each radiologist and the entire group. In the 2nd year, the number of breast cancers diagnosed increased 50% (from 121 to 181), with a 6.5% increase in patient volume. Sensitivity increased from 80% to 87%, and there was no change in the positive predictive value of 32%. Median tumor size and node positivity decreased. Most major variables of population and technical factors were unchanged. Diagnostic approach was altered during the 2nd year, as shown by a 50% increase in the use of spot compression, magnification views, and sonography. Analysis of each radiologist's performance before and after attending mammography courses showed similar changes. These data suggest that dedicated mammography courses can help improve radiologists' performance and alter their interpretive approach.  相似文献   
85.
Effects of physical activity on some components of the skeletal system.   总被引:1,自引:0,他引:1  
Sporting activities impose on the skeletal system forces of a high intensity and frequency. Ligaments, bone and tendons behave in a time-dependent load-extension fashion, and it is important for both scientists and clinicians to consider, for example, the alterations in failure properties shown by ligaments, tendons and bone at different rates of deformation. Whether the ability of the skeletal system to withstand stress can be improved with appropriate training is still controversial. The effects of physical exercise depend on the modality, intensity and duration with which the exercise itself is performed. Moreover, genetic factors, also influencing growth and hormonal status, may exert a significant influence on the response of a given tissue to an external load. Overloading may cause a lesion, and this may decrease or annihilate performance capability. The skeletal system may not be resistant enough, and so it may prove limiting to intensive physical activity. In vitro studies on resistance of a single tissue have not taken into consideration the specific resistance of that structure in vivo, and the results so obtained cannot be readily extrapolated to sporting activities, as in vivo muscles, joints, tendons, ligaments and cartilage act as one. This article reviews some of the possible beneficial and detrimental effects of intense exercise on various components of the skeletal system, focusing on its ability to withstand and adapt to stresses and allow maximal performance.  相似文献   
86.
Congenital hypoplasia of the adrenal glands (CHA) is a rare condition, particularly in the absence of a central nervous system (CNS) anomaly. Two major types of CHA have been described in the setting of an apparently normal CNS and pituitary: a cytomegalic type usually with X-linked recessive inheritance and a miniature adult type that, when hereditary, is an autosomal recessive trait. Glycerol kinase deficiency (GKD) is an X-linked recessive trait, and it may be associated with CHA and adrenal insufficiency, presumably because of deletion of adjacent X-linked loci. We report on three sibling infants, one male and two females, with normal CNS and lethal CHA of the miniature adult type, selective absence of pituitary LH; two of the infants also had glycerol kinase (GK) activity that was decreased but not in the GKD range. Restriction fragment length polymorphism (RFLP) analysis of X chromosome markers located at Xp21-p22 was carried out on the maternal grandfather, both parents, two of three affected infants, and a living normal brother. The results excluded the X-linked type of this disorder associated with GKD in this family. Autosomal recessive inheritance is most likely.  相似文献   
87.
Bilateral cerebellopontine angle tumors in neurofibromatosis type 2   总被引:3,自引:0,他引:3  
In a series of over 500 cases of cerebellopontine angle tumors, 19 patients had bilateral neurinomas. Four of these tumors arose from the facial rather than the acoustic nerve. A conservative policy regarding surgery had been adopted in an effort to prevent hearing loss for as long as possible. Nevertheless, all patients operated on in this series are now totally deaf. The results of managing these patients surgically and conservatively are discussed.  相似文献   
88.
Segments of nicotinic acetylcholine receptor α sub-unit genes have been isolated from a panel of insect species by polymerase chain reaction, using degenerate oligonucleotide primers designed to recognize conserved regions of the Drosophila melanogaster ALS and SAO genes. The amplified segments encode elements of typical a-subunits anticipated to play roles in ligand binding and ion channel formation. Each is also clearly either ALS or SAD-like. The predicted protein sequences display extremely high levels of conservation (over 85% for each subtype) even though derived from very distantly related insect species.  相似文献   
89.
Acute renal failure (ARF) is a serious complication in clients who have undergone bone marrow transplantation (BMT). The majority of cases develop as a result of intrarenal damage. Renal ischemia or nephrotoxic drugs, free hemoglobin, and free myoglobin contribute to acute tubular necrosis (ATN), which is the most likely cause of ARF in BMT clients. Nursing care of hospitalized BMT clients is directed toward the prevention of ARF by identifying clients who are at risk, the early diagnosis of renal impairment, and the administration of comprehensive treatment. Nurses play a vital role in the early diagnosis of renal impairment by assessing the client's fluid status, serum and urine electrolyte levels, and daily weights. The nursing role in managing clients with ARF includes preventing drug nephrotoxicity, maintaining fluid and electrolyte balance, preventing infection, and providing emotional support.  相似文献   
90.
Steroid receptor was assessed immunohistochemically in 158 samples of normal breast for variation through the menstrual cycle. Patterns and intensity of reaction were used in a semi-quantitative scoring system to examine the influence of cycle phase, cycle type, parity and age. The changes in oestrogen receptor for natural cycle and oral contraceptive (OC) cycles indicated down-regulation by progestins. Progesterone receptor did not vary significantly in natural cycles, but increased steadily through OC cycles. This study provides strong evidence that both oestrogen and progesterone influence breast epithelium, but dissimilarities from the endometrium are apparent. The interval since pregnancy had a significant negative effect on frequency and score of oestrogen receptor and score of progesterone receptor. Multivariate analysis established the phase of cycle and OC use as independent significant influences on oestrogen receptor. The interval since pregnancy was an independent significant factor for both oestrogen and progesterone receptor presence.  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