全文获取类型
收费全文 | 17695篇 |
免费 | 1515篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 151篇 |
儿科学 | 477篇 |
妇产科学 | 505篇 |
基础医学 | 2446篇 |
口腔科学 | 575篇 |
临床医学 | 2056篇 |
内科学 | 3144篇 |
皮肤病学 | 396篇 |
神经病学 | 1690篇 |
特种医学 | 799篇 |
外科学 | 2281篇 |
综合类 | 454篇 |
一般理论 | 17篇 |
预防医学 | 1981篇 |
眼科学 | 223篇 |
药学 | 1117篇 |
1篇 | |
中国医学 | 16篇 |
肿瘤学 | 919篇 |
出版年
2022年 | 139篇 |
2021年 | 254篇 |
2020年 | 190篇 |
2019年 | 295篇 |
2018年 | 347篇 |
2017年 | 256篇 |
2016年 | 249篇 |
2015年 | 279篇 |
2014年 | 399篇 |
2013年 | 603篇 |
2012年 | 826篇 |
2011年 | 829篇 |
2010年 | 500篇 |
2009年 | 452篇 |
2008年 | 703篇 |
2007年 | 741篇 |
2006年 | 681篇 |
2005年 | 694篇 |
2004年 | 691篇 |
2003年 | 661篇 |
2002年 | 639篇 |
2001年 | 607篇 |
2000年 | 662篇 |
1999年 | 559篇 |
1998年 | 233篇 |
1997年 | 191篇 |
1996年 | 222篇 |
1995年 | 177篇 |
1994年 | 146篇 |
1993年 | 148篇 |
1992年 | 435篇 |
1991年 | 403篇 |
1990年 | 408篇 |
1989年 | 370篇 |
1988年 | 317篇 |
1987年 | 331篇 |
1986年 | 294篇 |
1985年 | 303篇 |
1984年 | 282篇 |
1983年 | 231篇 |
1982年 | 136篇 |
1980年 | 132篇 |
1979年 | 199篇 |
1978年 | 148篇 |
1976年 | 126篇 |
1975年 | 139篇 |
1974年 | 143篇 |
1973年 | 145篇 |
1972年 | 148篇 |
1971年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
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
73.
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
74.
Congenital adrenal hypoplasia and selective absence of pituitary luteinizing hormone: a new autosomal recessive syndrome 总被引:1,自引:0,他引:1
B A Burke M R Wick R King T Thompson J Hansen B T Darrae U Francke W K Seltzer E R McCabe B W Scheithauer 《American journal of medical genetics》1988,31(1):75-97
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
75.
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
76.
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
77.
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
78.
S Battersby B J Robertson T J Anderson R J King K McPherson 《British journal of cancer》1992,65(4):601-607
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
79.
Drinking History Is Related to Persistent Blood Pressure Dysregulation in Postwithdrawal Alcoholics 总被引:1,自引:1,他引:0
Andrea C. King Oscar A. Parsons Nancy C. Bernardy William R. Lovallo 《Alcoholism, clinical and experimental research》1994,18(5):1172-1176
We have previously demonstrated that alcoholics with transitory (< 72 hr) elevations in blood pressure (BP) during withdrawal continue to show residual cardiovascular dysregulation up to 4 weeks of abstinence. The present study replicates and extends these findings. Alcoholic inpatients were divided into three subgroups ( ns = 14) based on BP during the first 72 hr of withdrawal: transitory hypertensives (tHTs; BP > 160/95 mm Hg), transitory borderline hypertensives (tBHs; 140/90 BP < 160/95), and normotensives (NTs; all BPs < 140/90). All patients had normal resting pressures after 72 hr of withdrawal. At 3–4 weeks postadmission, the alcoholics and 14 nonalcoholic controls (CONTs) were tested at rest and during a 5-min handgrip task. The tHTs showed an exaggerated systolic and diastolic BP response to handgrip compared with NTs and CONTs, with tBHs intermediate ( ps < 0.05). Drinking history showed the tHTs had the highest reported level of alcohol consumption and severity of withdrawal symptoms ( ps < 0.05). Regression analyses indicated that consumption of hard liquor was the variable most predictive of admission BPs; further, parental history of hypertension potentiated this relationship for systolic BP. Age and consumption of nicotine and caffeine were not significant predictors of admission BP. The results suggest a persistent cardiovascular dysregulation in alcoholics showing transient hypertensive withdrawal BPs. These alcoholics may be at increased risk for future alcohol-related cardiovascular disorder. 相似文献
80.
Training in élite young athletes (the Training of Young Athletes (TOYA) Study): injuries, flexibility and isometric strength.
下载免费PDF全文
![点击此处可从《British journal of sports medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Using a mixed longitudinal design, the incidence of injuries, and the development of flexibility and isometric strength of the upper and lower limbs were studied for 2 years in 453 élite young athletes (aged between 9 and 18 years) practising football, gymnastics, swimming or tennis. The children suffered from a low incidence of injuries. Strength and flexibility did not exert a significant role in determining injuries. The rate of injury was not significantly different between the 2 years of the study. Young swimmers showed a greater generalized flexibility. Girls were more flexible than boys between the ages of 13 to 16 years. Athletic children are able to exert greater isometric strength than normal schoolchildren. Boys diverged from the normal population at 14 years, while athletic girls were stronger at all ages. Girls were stronger than boys up to age 12, who were still increasing their muscle strength at 19 years. The average maximal isometric strength exerted in both upper and lower limbs in the four sports was not significantly different. Male gymnasts over 11 years old were significantly stronger than all other athletes. 相似文献