全文获取类型
收费全文 | 63858篇 |
免费 | 4151篇 |
国内免费 | 6篇 |
专业分类
68015篇 |
出版年
2023年 | 464篇 |
2022年 | 441篇 |
2021年 | 921篇 |
2020年 | 833篇 |
2019年 | 854篇 |
2018年 | 1976篇 |
2017年 | 1841篇 |
2016年 | 2397篇 |
2015年 | 3157篇 |
2014年 | 3139篇 |
2013年 | 4214篇 |
2012年 | 5049篇 |
2011年 | 4509篇 |
2010年 | 2806篇 |
2009年 | 2207篇 |
2008年 | 3498篇 |
2007年 | 3291篇 |
2006年 | 3104篇 |
2005年 | 2655篇 |
2004年 | 2595篇 |
2003年 | 2323篇 |
2002年 | 2134篇 |
2001年 | 1472篇 |
2000年 | 1446篇 |
1999年 | 1127篇 |
1998年 | 492篇 |
1997年 | 360篇 |
1996年 | 363篇 |
1995年 | 336篇 |
1994年 | 259篇 |
1993年 | 246篇 |
1992年 | 576篇 |
1991年 | 482篇 |
1990年 | 436篇 |
1989年 | 433篇 |
1988年 | 427篇 |
1987年 | 372篇 |
1986年 | 363篇 |
1985年 | 350篇 |
1984年 | 350篇 |
1983年 | 240篇 |
1982年 | 226篇 |
1980年 | 176篇 |
1979年 | 214篇 |
1978年 | 206篇 |
1975年 | 197篇 |
1974年 | 217篇 |
1973年 | 222篇 |
1972年 | 185篇 |
1969年 | 172篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
974.
Augusto García Villanueva María Jesús García Villanueva Mercedes García Villanueva Roberto Rojo Blanco María Vicenta Collado Guirao Jacobo Cabañas Montero Rafael Beni Pérez Irene Moreno Montes 《Endocrinología y nutrición》2013,60(5):254-259
Amyloidosis is an uncommon syndrome consisting of a number of disorders having in common an extracellular deposit of fibrillary proteins. This results in functional and structural changes in the affected organs, depending on deposit location and severity.Amyloid infiltration of the thyroid gland may occur in 50% and up to 80% of patients with primary and secondary amyloidosis respectively. Amyloid goiter (AG) is a true rarity, usually found associated to secondary amyloidosis. AG may require surgical excision, usually because of compressive symptoms.We report the case of a patient with a big AG occurring in the course of a secondary amyloidosis associated to polyarticular onset juvenile idiopathic arthritis who underwent total thyroidectomy. Current literature is reviewed, an attempt is made to provide action guidelines, and some surgical considerations on this rare condition are given. 相似文献
975.
976.
977.
Piotr Wysoczanski Robert J. Mart E. Joel Loveridge Christopher Williams Sara B.-M. Whittaker Matthew P. Crump Rudolf K. Allemann 《Biomolecular NMR assignments》2013,7(2):187-191
Here we report the 1H, 13C and 15N resonance assignments of free Bcl-xL and of Bcl-xL in complex with an azobenzene-modified peptide derived from the BH3 domain of the pro-apoptotic Bak. The spectra suggest predominantly folded proteins; chemical shift difference analysis provides a detailed view of the reorganization occurring on peptide binding. 相似文献
978.
Tomáš Mašek Václav Vopalenský Martin Pospíšek 《Central European Journal of Biology》2013,8(7):712-712
Paper by Masek et al. “The Luc2 gene enhances reliability of bicistronic assays” in Volume 8, Issue 5, 423–431 / May 2013; DOI: 10.2478/s11535-013-0151-z contains incomplete graphic file inserted as Figure 2. The correct Figure 2, together with its caption is presented below. 相似文献
979.
Maria Giné-Garriga Carme Martin-Borràs Anna Puig-Ribera Carlos Martín-Cantera Mercè Solà Antonio Cuesta-Vargas 《PloS one》2013,8(6)
Background
Effective promotion of exercise could result in substantial savings in healthcare cost expenses in terms of direct medical costs, such as the number of medical appointments. However, this is hampered by our limited knowledge of how to achieve sustained increases in physical activity.Objectives
To assess the effectiveness of a Primary Health Care (PHC) based physical activity program in reducing the total number of visits to the healthcare center among inactive patients, over a 15-month period.Research Design
Randomized controlled trial.Subjects
Three hundred and sixty-two (n = 362) inactive patients suffering from at least one chronic condition were included. One hundred and eighty-three patients (n = 183; mean (SD); 68.3 (8.8) years; 118 women) were randomly allocated to the physical activity program (IG). One hundred and seventy-nine patients (n = 179; 67.2 (9.1) years; 106 women) were allocated to the control group (CG). The IG went through a three-month standardized physical activity program led by physical activity specialists and linked to community resources.Measures
The total number of medical appointments to the PHC, during twelve months before and after the program, was registered. Self-reported health status (SF-12 version 2) was assessed at baseline (month 0), at the end of the intervention (month 3), and at 12 months follow-up after the end of the intervention (month 15).Results
The IG had a significantly reduced number of visits during the 12 months after the intervention: 14.8 (8.5). The CG remained about the same: 18.2 (11.1) (P = .002).Conclusions
Our findings indicate that a 3-month physical activity program linked to community resources is a short-duration, effective and sustainable intervention in inactive patients to decrease rates of PHC visits.Trial Registration
ClinicalTrials.gov NCT00714831相似文献980.
Cesar A. Olguin Tomas Landete-Castillejos Francisco Ceacero Andrés J. García Laureano Gallego 《PloS one》2013,8(6)
Few studies in wild animals have assessed changes in mineral profile in long bones and their implications for mechanical properties. We examined the effect of two diets differing in mineral content on the composition and mechanical properties of femora from two groups each with 13 free-ranging red deer hinds. Contents of Ca, P, Mg, K, Na, S, Cu, Fe, Mn, Se, Zn, B and Sr, Young’s modulus of elasticity (E), bending strength and work of fracture were assessed in the proximal part of the diaphysis (PD) and the mid-diaphysis (MD). Whole body measures were also recorded on the hinds. Compared to animals on control diets, those on supplemented diets increased live weight by 6.5 kg and their kidney fat index (KFI), but not carcass weight, body or organ size, femur size or cortical thickness. Supplemental feeding increased Mn content of bone by 23%, Cu by 9% and Zn by 6%. These differences showed a mean fourfold greater content of these minerals in supplemental diet, whereas femora did not reflect a 5.4 times greater content of major minerals (Na and P) in the diet. Lower content of B and Sr in supplemented diet also reduced femur B by 14% and Sr by 5%. There was a subtle effect of diet only on E and none on other mechanical properties. Thus, greater availability of microminerals but not major minerals in the diet is reflected in bone composition even before marked body effects, bone macro-structure or its mechanical properties are affected. 相似文献