全文获取类型
收费全文 | 1219篇 |
免费 | 50篇 |
国内免费 | 37篇 |
专业分类
儿科学 | 77篇 |
妇产科学 | 41篇 |
基础医学 | 72篇 |
口腔科学 | 34篇 |
临床医学 | 482篇 |
内科学 | 144篇 |
皮肤病学 | 6篇 |
神经病学 | 59篇 |
特种医学 | 114篇 |
外科学 | 37篇 |
综合类 | 33篇 |
预防医学 | 98篇 |
眼科学 | 7篇 |
药学 | 45篇 |
肿瘤学 | 57篇 |
出版年
2023年 | 5篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 17篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 63篇 |
2012年 | 19篇 |
2011年 | 11篇 |
2010年 | 31篇 |
2009年 | 39篇 |
2008年 | 24篇 |
2007年 | 36篇 |
2006年 | 30篇 |
2005年 | 20篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 32篇 |
2001年 | 38篇 |
2000年 | 32篇 |
1999年 | 40篇 |
1998年 | 93篇 |
1997年 | 87篇 |
1996年 | 81篇 |
1995年 | 66篇 |
1994年 | 51篇 |
1993年 | 58篇 |
1992年 | 20篇 |
1991年 | 32篇 |
1990年 | 33篇 |
1989年 | 25篇 |
1988年 | 36篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 5篇 |
1970年 | 5篇 |
排序方式: 共有1306条查询结果,搜索用时 0 毫秒
71.
Glioblastoma multiforme (GBM) is the most common type of primary malignant brain tumor. Although comprehensive therapeutic measures are available, recurrence is very frequent and the prognosis of GBM remains dismal. To date, little is known about the molecular pathogenesis associated with GBM recurrence. According to Knudson ' s two-hit hypothesis of tumor suppressor gene (TSG) inactivation,1 deletion of a chromosomal region, as revealed by loss of heterozygosity (LOH), is often indicative of the presence of a potential TSG. Allelotype studies involving a comprehensive LOH analysis of the whole genome can provide more detailed and thorough information for detecting genetic anomalies than traditional LOH analysis. The present study is designed to conduct a genome-wide allelotype analysis of one patient ' s primary and corresponding recurrent GBM tumors in an effort to reveal molecular genetic alterations associated with the recurrence of this malignancy. 相似文献
72.
73.
74.
75.
76.
Sternocostoclavicular hyperostosis is a benign ossifying diathesis of unknown etiology characterized by hyperostosis and soft-tissue ossification between the clavicles, anterior portion of the upper ribs, and manubrium, with variable hyperostosis or ankylosis in the spine and sacroiliac joints. Our cumulative experience with 11 cases is reported, with emphasis on radiographic features of the condition. Scintigraphic results in five patients and computed tomographic findings in one patient are presented. A review of the literature and our own material indicates that sternocostoclavicular hyperostosis may be more common than has been previously recognized. 相似文献
77.
Tamara D Simon Stephanie Phibbs L Miriam Dickinson Allison Kempe John F Steiner Arthur J Davidson Simon J Hambidge 《Ambulatory Pediatrics》2006,6(6):318-325
OBJECTIVE: To describe clinician delivery of injury prevention anticipatory guidance and injury visits in a birth cohort, and to describe the association of injury prevention anticipatory guidance with subsequent injury visits. METHODS: We performed a prospective cohort study of 2610 infants born from July 1, 1998 to June 30, 1999, at an urban safety-net hospital and seen subsequently for well child care (WCC, visits = 10558) and/or injury by 16 months of age. Injury guidance was defined as the proportion of recommended injury prevention anticipatory guidance items delivered to those expected, given the WCC visits the child attended. The outcome was a first injury visit to a clinic, emergency department, or hospital. RESULTS: The injury prevention items most discussed were car seats (84%-95% of all WCC visits) and rolling over at the 2-month WCC visit (80%). Other items were addressed at 36%-69% of visits. A total of 1931 (74%) of children received > or = 50% expected injury guidance. A total of 277 children (11%) had an injury visit, primarily for minor injuries. In unadjusted analysis, children receiving < 25% expected injury guidance were more likely to have a subsequent injury visit (unadjusted odds ratio 6.2; 95% confidence interval [95% CI] 3.2-9.7). In adjusted analysis, children who received < 25% and 25%-49% expected injury guidance were more likely to have a subsequent injury visits (adjusted odds ratio [AOR] 6.6; 95% CI 3.8-11.2; and AOR 2.9, 95% CI 2.0-4.3, respectively). CONCLUSIONS: Disadvantaged children whose families received less injury guidance than other children in their cohort were more likely to have a subsequent injury visit. Further studies are needed to determine whether increased injury prevention counseling reduces injury visits. 相似文献
78.
Erin S Calipari Mark J Ferris Benjamin A Zimmer David CS Roberts Sara R Jones 《Neuropsychopharmacology》2013,38(12):2385-2392
The dopamine transporter (DAT) is responsible for terminating dopamine (DA) signaling and is the primary site of cocaine''s reinforcing actions. Cocaine self-administration has been shown previously to result in changes in cocaine potency at the DAT. To determine whether the DAT changes associated with self-administration are due to differences in intake levels or temporal patterns of cocaine-induced DAT inhibition, we manipulated cocaine access to produce either continuous or intermittent elevations in cocaine brain levels. Long-access (LgA, 6 h) and short-access (ShA, 2 h) continuous self-administration produced similar temporal profiles of cocaine intake that were sustained throughout the session; however, LgA had greater intake. ShA and intermittent-access (IntA, 6 h) produced the same intake, but different temporal profiles, with ‘spiking'' brain levels in IntA compared with constant levels in ShA. IntA consisted of 5-min access periods alternating with 25-min timeouts, which resulted in bursts of high responding followed by periods of no responding. DA release and uptake, as well as the potency of cocaine for DAT inhibition, were assessed by voltammetry in the nucleus accumbens slices following control, IntA, ShA, and LgA self-administration. Continuous-access protocols (LgA and ShA) did not change DA parameters, but the ‘spiking'' protocol (IntA) increased both release and uptake of DA. In addition, high continuous intake (LgA) produced tolerance to cocaine, while ‘spiking'' (IntA) produced sensitization, relative to ShA and naive controls. Thus, intake and pattern can both influence cocaine potency, and tolerance seems to be produced by high intake, while sensitization is produced by intermittent temporal patterns of intake. 相似文献
79.
80.
This study examines whether the passage of California's Proposition 187, a proposition designed to restrict undocumented immigrants from using public services, had a negative effect on the use of prenatal care and birth outcomes. Comparisons of prenatal care use and birth outcomes before and after the passage of the proposition are made between low-education foreign-born and U.S.-born mothers using California's Birth Public Use files. Multivariate linear and logistic regressions were used to control for regional and maternal characteristics. We find a significant but small decline in the use of prenatal care by low-education foreign-born women after Proposition 187 passed; however, there was no detectable deterioration of birth outcomes. Whether future reductions in the availability of prenatal care would damage the health of children is unclear. 相似文献