全文获取类型
收费全文 | 16046篇 |
免费 | 1311篇 |
国内免费 | 904篇 |
出版年
2024年 | 40篇 |
2023年 | 174篇 |
2022年 | 357篇 |
2021年 | 579篇 |
2020年 | 436篇 |
2019年 | 534篇 |
2018年 | 649篇 |
2017年 | 455篇 |
2016年 | 670篇 |
2015年 | 957篇 |
2014年 | 1156篇 |
2013年 | 1277篇 |
2012年 | 1499篇 |
2011年 | 1323篇 |
2010年 | 867篇 |
2009年 | 676篇 |
2008年 | 891篇 |
2007年 | 772篇 |
2006年 | 660篇 |
2005年 | 616篇 |
2004年 | 620篇 |
2003年 | 562篇 |
2002年 | 453篇 |
2001年 | 286篇 |
2000年 | 256篇 |
1999年 | 243篇 |
1998年 | 124篇 |
1997年 | 98篇 |
1996年 | 77篇 |
1995年 | 86篇 |
1994年 | 76篇 |
1993年 | 55篇 |
1992年 | 78篇 |
1991年 | 75篇 |
1990年 | 55篇 |
1989年 | 42篇 |
1988年 | 50篇 |
1987年 | 27篇 |
1986年 | 32篇 |
1985年 | 30篇 |
1984年 | 32篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 16篇 |
1979年 | 15篇 |
1976年 | 15篇 |
1975年 | 14篇 |
1973年 | 25篇 |
1972年 | 15篇 |
1958年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
991.
It has been more than a year since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged. Many studies have provided insights into the various aspects of the immune response in coronavirus disease 2019 (COVID-19). Especially for antibody treatment and vaccine development, humoral immunity to SARS-CoV-2 has been studied extensively, though there is still much that is unknown and controversial. Here, we introduce key discoveries on the humoral immune responses in COVID-19, including the immune dynamics of antibody responses and correlations with disease severity, neutralizing antibodies and their cross-reactivity, how long the antibody and memory B-cell responses last, aberrant autoreactive antibodies generated in COVID-19 patients, and the efficacy of currently available therapeutic antibodies and vaccines against circulating SARS-CoV-2 variants, and highlight gaps in the current knowledge. 相似文献
992.
Xiao-Jun Ji He HuangJun Du Jian-Guo ZhuLu-Jing Ren Shuang LiZhi-Kui Nie 《Bioresource technology》2009,100(21):5214-5218
An industrial medium containing urea as a sole nitrogen source, low levels of corn steep liquor and mineral salts as nutrition factors to retain high 2,3-butanediol production through co-fermentation of glucose and xylose (2:1, wt/wt) by Klebsiella oxytoca was developed. Urea and corn steep liquor were identified as the most significant factors by the two-level Plackett–Burman design. Steepest ascent experiments were applied to approach the optimal region of the two factors and a central composite design was employed to determine their optimal levels. Under the optimal medium, the yield of 2,3-butanediol plus acetoin relative to glucose and xylose was up to 0.428 g/g, which was 85.6% of theoretical value. The cheap nitrogen source and nutrition factors combining the co-fermentation process using lignocellulose derived glucose and xylose as the carbon source in the developed medium would be a potential solution to improve the economics of microbial 2,3-butanediol production. 相似文献
993.
Excellent Compatibility of Solvate Ionic Liquids with Sulfide Solid Electrolytes: Toward Favorable Ionic Contacts in Bulk‐Type All‐Solid‐State Lithium‐Ion Batteries
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
995.
996.
Lithium‐Ion Batteries: Excellent Compatibility of Solvate Ionic Liquids with Sulfide Solid Electrolytes: Toward Favorable Ionic Contacts in Bulk‐Type All‐Solid‐State Lithium‐Ion Batteries (Adv. Energy Mater. 22/2015)
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
997.
998.
ObjectiveTo evaluate the clinical efficacy of sorafenib as preoperative neoadjuvant therapy in patients with high risk renal cell carcinoma (RCC).ResultsAmong the 18 patients there were 13 male and 5 female, with a median age of 54.6 years. The objective response rate (ORR) of the operation on the selected patients is very high (94.4%), including 4 cases (22.2%) of partial response (PR) and 13 cases (72.2%) of stable disease (SD). After preoperative sorafenib treatment, the average tumor size of the 18 patients decreased from 7.8 cm (ranging from 3.6 to 19.2 cm) to 6.2 cm (ranging from 2.4 to 16.8 cm), and the median value of average tumor CT value decreased from 61HU to 52 HU. Among the 5 patients who had IVC tumor thrombi, the grades of tumor thrombi in 2 patients who were grade II before sorafenib treatment became grade I and grade 0 respectively, 2 patients of grade III both became grade II.ConclusionPreoperative neoadjuvant therapy with sorafenib for high risk RCC patients can significantly decrease primary tumor volume as well as tumor thrombus, which could help the nephron-sparing surgery (NSS) or radical nephrectomy to be done successfully. 相似文献
999.
Zi Feng Yang Chris Ka Pun Mok Xiao Qing Liu Xiao Bo Li Jian Feng He Wen Da Guan Yong Hao Xu Wei Qi Pan Li Yan Chen Yong Ping Lin Shi Guan Wu Si Hua Pan Ji Cheng Huang Guo Yun Ding Kui Zheng Chang Wen Ke Jin Yan Lin Yong Hui Zhang Horace Hok Yeung Lee Wen Kuan Liu Chun Guang Yang Rong Zhou Joseph Sriyal Malik Peiris Yi Min Li Rong Chang Chen Ling Chen Nan Shan Zhong 《PloS one》2015,10(2)
BackgroundThe second wave of avian influenza H7N9 virus outbreak in humans spread to the Guangdong province of China by August of 2013 and this virus is now endemic in poultry in this region.MethodsFive patients with H7N9 virus infection admitted to our hospital during August 2013 to February 2014 were intensively investigated. Viral load in the respiratory tract was determined by quantitative polymerase chain reaction (Q-PCR) and cytokine levels were measured by bead-based flow cytometery.ResultsFour patients survived and one died. Viral load in different clinical specimens was correlated with cytokine levels in plasma and broncho-alveolar fluid (BALF), therapeutic modalities used and clinical outcome. Intravenous zanamivir appeared to be better than peramivir as salvage therapy in patients who failed to respond to oseltamivir. Higher and more prolonged viral load was found in the sputum or endotracheal aspirates compared to throat swabs. Upregulation of proinflammatory cytokines IP-10, MCP-1, MIG, MIP-1α/β, IL-1β and IL-8 was found in the plasma and BALF samples. The levels of cytokines in the plasma and viral load were correlated with disease severity. Reactivation of herpes simplex virus type 1(HSV-1) was found in three out of five patients (60%).ConclusionExpectorated sputum or endotracheal aspirate specimens are preferable to throat swabs for detecting and monitoring H7N9 virus. Severity of the disease was correlated to the viral load in the respiratory tract as well as the extents of cytokinemia. Reactivation of HSV-1 may contribute to clinical outcome. 相似文献
1000.
Won Soon Park Se In Sung So Yoon Ahn Hye Soo Yoo Dong Kyung Sung Geun Ho Im Soo Jin Choi Yun Sil Chang 《PloS one》2015,10(3)
Though hypothermia is the only clinically available treatment for neonatal hypoxic-ischemic encephalopathy (HIE), it is not completely effective in severe cases. We hypothesized that combined treatment with hypothermia and transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) would synergistically attenuate severe HIE compared to stand-alone therapy. To induce hypoxia-ischemia (HI), male Sprague-Dawley rats were subjected to 8% oxygen for 120 min after unilateral carotid artery ligation on postnatal day (P) 7. After confirmation of severe HIE involving >50% of the ipsilateral hemisphere volume as determined by diffusion-weighted brain magnetic resonance imaging (MRI) within 2 h after HI, intraventricular MSC transplantation (1 × 105 cells) and/or hypothermia with target temperature at 32°C for 24 h were administered 6 h after induction of HI. Follow-up brain MRI at P12 and P42, sensorimotor function tests at P40–42, evaluation of cytokines in the cerebrospinal fluid (CSF) at P42, and histologic analysis of peri-infarct tissues at P42 were performed. Severe HI resulted in progressively increased brain infarction over time as assessed by serial MRI, increased number of cells positive for terminal deoxynucleotidyl transferase nick-end labeling, microgliosis and astrocytosis, increased CSF cytokine levels, and impaired function in behavioral tests such as rotarod and cylinder tests. All of the abnormalities observed in severe HIE showed greater improvement after combined treatment with hypothermia and MSC transplantation than with either therapy alone. Overall, these findings suggest that combined treatment with hypothermia and human UCB-derived MSC transplantation might be a novel therapeutic modality to improve the prognosis of severe HIE, an intractable disease that currently has no effective treatment. 相似文献