全文获取类型
收费全文 | 93620篇 |
免费 | 7940篇 |
国内免费 | 151篇 |
专业分类
耳鼻咽喉 | 989篇 |
儿科学 | 3088篇 |
妇产科学 | 2335篇 |
基础医学 | 11929篇 |
口腔科学 | 1463篇 |
临床医学 | 11396篇 |
内科学 | 17284篇 |
皮肤病学 | 1675篇 |
神经病学 | 9772篇 |
特种医学 | 2895篇 |
外国民族医学 | 4篇 |
外科学 | 11361篇 |
综合类 | 1140篇 |
现状与发展 | 1篇 |
一般理论 | 120篇 |
预防医学 | 11170篇 |
眼科学 | 2005篇 |
药学 | 6464篇 |
2篇 | |
中国医学 | 108篇 |
肿瘤学 | 6510篇 |
出版年
2023年 | 581篇 |
2022年 | 766篇 |
2021年 | 2362篇 |
2020年 | 1392篇 |
2019年 | 2317篇 |
2018年 | 2505篇 |
2017年 | 1973篇 |
2016年 | 2080篇 |
2015年 | 2244篇 |
2014年 | 3111篇 |
2013年 | 4333篇 |
2012年 | 6342篇 |
2011年 | 6376篇 |
2010年 | 3508篇 |
2009年 | 2971篇 |
2008年 | 5230篇 |
2007年 | 5378篇 |
2006年 | 5057篇 |
2005年 | 4742篇 |
2004年 | 4301篇 |
2003年 | 3756篇 |
2002年 | 3534篇 |
2001年 | 1729篇 |
2000年 | 1685篇 |
1999年 | 1575篇 |
1998年 | 819篇 |
1997年 | 707篇 |
1996年 | 641篇 |
1995年 | 607篇 |
1994年 | 509篇 |
1993年 | 440篇 |
1992年 | 1219篇 |
1991年 | 1208篇 |
1990年 | 1137篇 |
1989年 | 1135篇 |
1988年 | 934篇 |
1987年 | 1050篇 |
1986年 | 974篇 |
1985年 | 981篇 |
1984年 | 795篇 |
1983年 | 651篇 |
1982年 | 408篇 |
1979年 | 709篇 |
1978年 | 542篇 |
1977年 | 458篇 |
1976年 | 470篇 |
1975年 | 410篇 |
1974年 | 524篇 |
1973年 | 471篇 |
1972年 | 394篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Bradley J Catalone Shendra R Miller Mary Lee Ferguson Dan Malamud Tina Kish-Catalone Nina J Thakkar Fred C Krebs Mary K Howett Brian Wigdahl 《Biomedicine & Pharmacotherapy》2005,59(8):430-437
C31G, which has potent activity against the human immunodeficiency virus type 1 (HIV-1) and an established record of safety in animal studies and human trials, is a microbicidal agent comprised of a buffered equimolar mixture of two amphoteric, surface-active agents: an alkyl amine oxide (C14AO) and an alkyl betaine (C16B). Studies of long-term in vitro exposure to C31G and its constituents have suggested that the components of C31G may contribute differentially to its toxicity and efficacy. In the present studies, in vitro assays of cytotoxicity and anti-HIV-1 activity demonstrated that C16B was slightly less cytotoxic compared to either C31G or C14AO, whereas the anti-HIV-1 activities of C31G and its individual constituents were similar. In the murine model of cervicovaginal microbicide toxicity, in vivo exposure to C14AO resulted in severe cervical inflammation followed by a delayed disruption of the columnar epithelium. In contrast, exposure to C16B caused severe cervical epithelial disruption and a secondary, less intense inflammatory response. These results demonstrate that (i) there are both mechanistic and temporal differences in toxicity associated with the components of C31G not necessarily predicted by in vitro assessments of cytotoxicity and (ii) contributions of each component to the anti-HIV-1 activity of C31G appear to be equal. In addition, these findings indicate that direct and indirect mechanisms of in vivo toxicity can be observed as separate but interrelated events. These results provide further insight into the activity of C31G, as well as mechanisms potentially associated with microbicide toxicity. 相似文献
92.
Joseph F Malouf Manfredi Ballo Heidi M Connolly David O Hodge Regina M Herges Charles J Mullany Fletcher A Miller 《Journal of the American Society of Echocardiography》2005,18(3):252-256
The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses. 相似文献
93.
R H Miller M S Linet M L Van Natta L D McCaffrey R L Humphrey 《Archives of internal medicine》1987,147(9):1614-1617
Serum protein electrophoresis (SPEP) data obtained at diagnosis were available for 98 of 342 patients with chronic lymphocytic leukemia (CLL) identified in a population-based case-control epidemiologic study. Patients tested with SPEP at diagnosis were significantly younger, more likely to have lymphadenopathy, and more likely to have had their conditions diagnosed at a university hospital than those not tested. Four categories of electrophoretic patterns were identified: normal (N = 56), hypogammaglobulinemia (N = 28), hypergammaglobulinemia (N = 11), and monoclonal gammopathy (N = 3). A higher proportion of those with hypergammaglobulinemia were black, and patients with hypergammaglobulinemia and monoclonal gammopathy were more likely to die within the first year following diagnosis than patients in the other SPEP groups. No association was found, however, between SPEP pattern and a clinical staging classification for CLL. These findings suggest that SPEP may be a useful adjunct in categorizing possible subtypes of CLL and developing future clinical staging classifications. 相似文献
94.
95.
Influence of Genetic Variation in the C-Reactive Protein Gene on the Inflammatory Response During and After Acute Coronary Ischemia 总被引:4,自引:0,他引:4
J. Suk Danik D. I. Chasman C. P. Cannon D. T. Miller R. Y. L. Zee P. Kozlowski D. J. Kwiatkowski P. M. Ridker 《Annals of human genetics》2006,70(6):705-716
The aim of this research was to assess whether common genetic variants within the C-reactive protein gene ( CRP ) are related to the degree of acute rise in plasma C-reactive protein (CRP) levels following an acute coronary syndrome (ACS). While polymorphisms within CRP are associated with basal CRP levels in healthy men and women, less is known about the relationship of such genetic variants and the degree of CRP rise during and after acute ischemia. Plasma CRP is associated with increased rates of recurrent coronary events. We evaluated seven common genetic variants within CRP and assessed their relationship to the degree of rise in CRP levels immediately following an acute coronary syndrome in 1827 European American patients. Variants in the putative promoter region, −757T > C and −286C > T > A, were associated with the highest CRP elevations after ACS. Patients with two copies of the A allele of SNP −286C > T > A had median CRP values of 76.6 mg/L, compared to 11.1 mg/L in patients with no copies of the rare variant (p-value <0.0001), post ACS. The lowest CRP values were found for patients with minor alleles of the exonic 1059G > C and the 3'untranslated region 1846G > A SNPs. For example, patients homozygous for the minor allele of 1059G > C had 71% lower median CRP values than those homozygous for the major allele [3.5 vs 12.0 mg/L, p < 0.0001]. These trends persisted in the chronic stable phase after ischemia had resolved, and after adjustment for infarct size by peak creatinine kinase levels and clinical status by Killip class. Assessment of CRP genetic variants identified patients with higher and lower CRP elevation after acute coronary syndrome. 相似文献
96.
M. Laurin Council Jennifer M. Gardner Cynthia Helms Ying Liu Lynn A. Cornelius Anne M. Bowcock 《Experimental dermatology》2009,18(5):485-487
Abstract: The risks of developing malignant melanoma (MM) include ultraviolet irradiation and genetic factors. To examine the contribution of rare and common variation within known MM genes in sporadic US MM patients, coding regions of known MM susceptibility genes [cyclin-dependent kinase inhibitor 2A ( CDKN2A ), cyclin-dependent kinase 4, melanocortin 1 receptor ( MC1R ) and tyrosinase ( TYR )] were resequenced in 109–135 MM cases. The significance of variants was examined by comparing their frequencies in 390 cancer-free controls. Potential deleterious mutations in CDKN2A were found in two patients and two others had variants of unknown significance. Cases were more likely than controls to harbour the MC1R 'R' variants known or predicted to alter its function ( P = 0.002), particularly the R160W variant ( P = 0.0035). The associated TYR R402Q variant (rs1126809*A) was found in 29% of cases, similar to what has been described previously. One MM patient with a family history of MM, who had developed other skin cancers, was homozygous for a novel TYR variant (P406L) of unknown significance. Hence, rare variants in TYR may be important risk factors for skin cancer. 相似文献
97.
Betsy D. Kennard Susan G. Silva Simon Tonev Paul Rohde Jennifer L. Hughes Benedetto Vitiello Christopher J. Kratochvil John F. Curry Graham J. Emslie Mark Reinecke John March 《Journal of the American Academy of Child and Adolescent Psychiatry》2009,48(2):186-195
ObjectiveWe examine remission rate probabilities, recovery rates, and residual symptoms across 36 weeks in the Treatment for Adolescents with Depression Study (TADS).MethodThe TADS, a multisite clinical trial, randomized 439 adolescents with major depressive disorder to 12 weeks of treatment with fluoxetine, cognitive–behavioral therapy, their combination, or pill placebo. The pill placebo group, treated openly after week 12, was not included in the subsequent analyses. Treatment differences in remission rates and probabilities of remission over time are compared. Recovery rates in remitters at weeks 12 (acute phase remitters) and 18 (continuation phase remitters) are summarized. We also examined whether residual symptoms at the end of 12 weeks of acute treatment predicted later remission.ResultsAt week 36, the estimated remission rates for intention-to-treat cases were as follows: combination, 60%; fluoxetine, 55%; cognitive–behavioral therapy, 64%; and overall, 60%. Paired comparisons reveal that, at week 24, all active treatments converge on remission outcomes. The recovery rate at week 36 was 65% for acute phase remitters and 71% for continuation phase remitters, with no significant between-treatment differences in recovery rates. Residual symptoms at the end of acute treatment predicted failure to achieve remission at weeks 18 and 36.ConclusionsMost depressed adolescents in all three treatment modalities achieved remission at the end of 9 months of treatment. 相似文献
98.
Paul M. Brunet Jennifer J. Heisz Catherine J. Mondloch David I. Shore Louis A. Schmidt 《Journal of anxiety disorders》2009,23(7):909-914
Contrary to popular beliefs, a recent empirical study using eye tracking has shown that a non-clinical sample of socially anxious adults did not avoid the eyes during face scanning. Using eye-tracking measures, we sought to extend these findings by examining the relation between stable shyness and face scanning patterns in a non-clinical sample of 11-year-old children. We found that shyness was associated with longer dwell time to the eye region than the mouth, suggesting that some shy children were not avoiding the eyes. Shyness was also correlated with fewer first fixations to the nose, which is thought to reflect the typical global strategy of face processing. Present results replicate and extend recent work on social anxiety and face scanning in adults to shyness in children. These preliminary findings also provide support for the notion that some shy children may be hypersensitive to detecting social cues and intentions in others conveyed by the eyes. Theoretical and practical implications for understanding the social cognitive correlates and treatment of shyness are discussed. 相似文献
99.
100.
Megan A. O’Grady Kristina Wilson Jennifer J. Harman 《The journal of primary prevention》2009,30(6):716-731
The purpose of this study was to evaluate a single-session peer-led safer sex intervention, based on the Information-Motivation-Behavioral
Skills theoretical model, for college students residing in campus residence halls. Participants (N = 108) were assigned to either an hour long control or 5-module intervention session. Compared to the control condition,
the intervention increased participants’ information and women’s subjective norms about preventative behavior. Both the control
and intervention sessions increased intentions to perform preventative behaviors (e.g., keep condoms available). These preliminary
results suggest that this intervention is promising for increasing constructs associated with safer sexual behavior and could
easily be implemented by residence hall staff. 相似文献