全文获取类型
收费全文 | 24756篇 |
免费 | 1272篇 |
国内免费 | 30篇 |
专业分类
26058篇 |
出版年
2023年 | 192篇 |
2022年 | 450篇 |
2021年 | 807篇 |
2020年 | 481篇 |
2019年 | 514篇 |
2018年 | 762篇 |
2017年 | 696篇 |
2016年 | 940篇 |
2015年 | 1085篇 |
2014年 | 1379篇 |
2013年 | 1867篇 |
2012年 | 2013篇 |
2011年 | 1766篇 |
2010年 | 1055篇 |
2009年 | 914篇 |
2008年 | 1085篇 |
2007年 | 1062篇 |
2006年 | 871篇 |
2005年 | 852篇 |
2004年 | 671篇 |
2003年 | 618篇 |
2002年 | 550篇 |
2001年 | 481篇 |
2000年 | 429篇 |
1999年 | 390篇 |
1998年 | 168篇 |
1997年 | 130篇 |
1996年 | 126篇 |
1995年 | 125篇 |
1994年 | 104篇 |
1993年 | 94篇 |
1992年 | 268篇 |
1991年 | 229篇 |
1990年 | 236篇 |
1989年 | 182篇 |
1988年 | 225篇 |
1987年 | 186篇 |
1986年 | 154篇 |
1985年 | 167篇 |
1984年 | 161篇 |
1983年 | 108篇 |
1982年 | 104篇 |
1981年 | 133篇 |
1980年 | 103篇 |
1979年 | 149篇 |
1978年 | 96篇 |
1977年 | 107篇 |
1975年 | 89篇 |
1974年 | 86篇 |
1973年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
In a double-blind study patients given a single dose of doxapram 1-5-2-0 mg/kg combined with morphine postoperatively had a significantly lower incidence of reflex postoperative cough and expectoration of purulent sputum than patients given morphine alone. They also had significantly higher arterial oxygen tensions five days postoperatively. Smaller differences were found with naloxone combined with morphine. 相似文献
94.
95.
S. Gupta 《Journal of fish biology》1975,7(1):71-76
Some observations on the biology of Cirrhinus reba (Cuvier) from Muzaffarnagar (U.P., India) have been made during the period July 1966 to June 1969. In C. reba both males and females mature simultaneously. The gonads attain the maximum weight in June and minimum in November. There is a definite seasonal cycle in relative condition. The relative condition in both male and female is highest in June preceeding the period of breeding. It is the gonad weight which influences the fluctuations of the relative condition. The visceral weight does not exert any significant effect on it. It is found possible to determine the spawning season and its extent, from the seasonal fluctuations of the relative condition. The present studies have also thrown light on the maturation and spawning habits of C. reba . The fish has only one spawning season of short duration, running from July to early September. In a mature ovary, the mature ova form only one mode which is sharply distinguished from the immature stock. 相似文献
96.
A major limitation of gene expression biomarker studies is that they are not reproducible as they simply do not generalize to larger, real-world, heterogeneous populations. Frequentist multi-cohort gene expression meta-analysis has been frequently used as a solution to this problem to identify biomarkers that are truly differentially expressed. However, the frequentist meta-analysis framework has its limitations–it needs at least 4–5 datasets with hundreds of samples, is prone to confounding from outliers and relies on multiple-hypothesis corrected p-values. To address these shortcomings, we have created a Bayesian meta-analysis framework for the analysis of gene expression data. Using real-world data from three different diseases, we show that the Bayesian method is more robust to outliers, creates more informative estimates of between-study heterogeneity, reduces the number of false positive and false negative biomarkers and selects more generalizable biomarkers with less data. We have compared the Bayesian framework to a previously published frequentist framework and have developed a publicly available R package for use. 相似文献
97.
Protha Biswas Uttpal Anand Suchismita Chatterjee Saha Nishi Kant Tulika Mishra Harison Masih Ananya Bar Devendra Kumar Pandey Niraj
Kumar Jha Madhumita Majumder Neela Das Vijaykumar
Shivaji Gadekar Mahipal S. Shekhawat Manoj Kumar Radha Jarosaw Prokw Jos M. Prez de la Lastra Abhijit Dey 《Journal of cellular and molecular medicine》2022,26(11):3083
98.
Anjali Manocha Flora Gupta Rajneesh Jain Seema Bhargava Mamta Kankra Sabari Das L. M. Srivastava 《Molecular and cellular biochemistry》2014,389(1-2):59-68
Coronary artery disease (CAD) affects Indians 5–6 years earlier than in the west, is diffuse and malignant, and poses a heavy burden on India’s developing economy. Traditional risk factors have failed to explain this high incidence of premature CAD and hence this study investigated the association of two novel risk biomarkers, cystatin C and small dense LDL (sdLDL) with the presence and severity of CAD. Cystatin C and sdLDL were estimated in 204 CAD patients ≤45 years of age and compared with 161 age-matched healthy controls. The traditional lipid profile parameters, i.e., cholesterol, LDL, HDL, triglycerides, apolipoproteins A1 and B, and Lp(a) were also measured in both groups. Cystatin C was significantly raised and mean LDL particle size significantly reduced in CAD patients as compared to controls. 62.7 % of CAD patients showed pattern B while 37.3 % patients showed pattern A. Of the traditional lipid tests, only HDL and apolipoprotein A1 showed a significant decrease in the CAD group. sdLDL was significantly associated with the severity of CAD, while cystatin C was not. Both cystatin C and sdLDL emerged as independent risk factors, however, of the two, sdLDL was a more sensitive predictor of CAD events. Cystatin C and mean LDL particle size are significantly and independently associated with the presence of CAD events in patients ≤45 years with normal kidney function. Hence, these novel risk biomarkers can be useful tools in reducing the morbidity and mortality associated with CAD in the productive Indian workforce. 相似文献
99.
Background and aims
Sustained interaction of advanced glycation end products (AGEs) with their receptor RAGE and subsequent signaling plays an important role in the development of diabetic complications. Genetic variation of RAGE gene may be associated with the development of vascular complications in type 2 diabetes mellitus (T2DM).Objectives
The present study aimed to explore the possible association of RAGE gene polymorphisms namely − 374T/A, − 429T/C and G82S with serum level of AGEs, paraoxonase (PON1) activity and macro-vascular complications (MVC) in Indian type 2 diabetes mellitus patients (T2DM).Methods
A total of 265 diabetic patients, including DM without any complications (n = 135), DM-MVC (n = 130) and 171 healthy individuals were enrolled. Genotyping of RAGE variants were assessed by polymerase chain reaction-restriction fragment length polymorphism. Serum AGEs were estimated by ELISA and fluorometrically. and PON1 activity was assessed spectrophotometrically.Results
Of the three examined SNPs, association of − 429T/C polymorphism with MVC in T2DM was observed (OR = 3.001, p = 0.001) in the dominant model. Allele ‘A’ of − 374T/A polymorphism seems to confer better cardiac outcome in T2DM. Patients carrying C allele (− 429T/C) and S allele (G82S) had significantly higher AGEs levels. − 429T/C polymorphism was also found to be associated with low PON1 activity. Interaction analysis revealed that the risk of development of MVC was higher in T2DM patients carrying both a CC genotype of − 429T/C polymorphism and a higher level of AGEs (OR = 1.343, p = 0.040).Conclusion
RAGE gene polymorphism has a significant effect on AGEs level and PON1 activity in diabetic subjects compared to healthy individuals. Diabetic patients with a CC genotype of − 429T/C are prone to develop MVC, more so if AGEs levels are high and PON1 activity is low. 相似文献100.
Reelin is an extracellular matrix molecule that is involved in the normal development of the cerebellar lamination, Bergmann glial fibres alignment, Purkinje cell monolayer arrangement and granule cell migration. In this study, we have examined the effects of maternal exposure of deltamethrin (DLT), a type II pyrethroid insecticide, on the structural and functional development of rat cerebellum during postnatal life. DLT (0.75 mg/kg body weight, intraperitoneally dissolved in dimethylsulphoxide) was administered in timed pregnant rats during two different gestational time periods, i.e. gestational days of 7–10 and 11–14, respectively. In DLT exposed rats, a significant overexpression of reelin was observed in the cells of the external granule cell layer (EGL) and internal granule cell layer along with an ectopic expression of reelin in the EGL as well as in the migrating granule cells just below the EGL, revealing an arrest of granule cell migration in this zone. Mis-orientation and hypertrophy of the Bergmann glial fibres further hampered the journey of the granule cells to their final destination. Possibly reelin overexpression also caused misalignment of the Purkinje cells and inhibited the neurite growth leading to a significant decrease in the spine density, main dendritic length and width of the dendritic arbour. Thus, it is proposed that the DLT exerts its neurotoxic effects possibly via the intracellular accumulation and low release of reelin leading to an impaired granule cell and Purkinje cell migration, inhibition of neurite outgrowth and reduced spine density. Such impaired cerebellar development leads to motor coordination deficits. 相似文献