全文获取类型
收费全文 | 3449篇 |
免费 | 56篇 |
国内免费 | 8篇 |
学科分类
工业技术 | 3513篇 |
出版年
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 43篇 |
2012年 | 33篇 |
2011年 | 58篇 |
2010年 | 42篇 |
2009年 | 50篇 |
2008年 | 49篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 37篇 |
2004年 | 30篇 |
2003年 | 39篇 |
2002年 | 32篇 |
2001年 | 27篇 |
2000年 | 12篇 |
1999年 | 103篇 |
1998年 | 731篇 |
1997年 | 447篇 |
1996年 | 272篇 |
1995年 | 175篇 |
1994年 | 153篇 |
1993年 | 176篇 |
1992年 | 43篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 37篇 |
1988年 | 44篇 |
1987年 | 44篇 |
1986年 | 33篇 |
1985年 | 34篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 28篇 |
1981年 | 30篇 |
1980年 | 38篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 78篇 |
1976年 | 155篇 |
1975年 | 31篇 |
1974年 | 16篇 |
1973年 | 10篇 |
1971年 | 9篇 |
排序方式: 共有3513条查询结果,搜索用时 359 毫秒
1.
MA Nowak AL Lloyd GM Vasquez TA Wiltrout LM Wahl N Bischofberger J Williams A Kinter AS Fauci VM Hirsch JD Lifson 《Canadian Metallurgical Quarterly》1997,71(10):7518-7525
Mathematical modeling of viral replication dynamics, based on sequential measurements of levels of virion-associated RNA in plasma during antiretroviral treatment, has led to fundamental new insights into human immunodeficiency virus type 1 pathogenesis. We took advantage of the simian immunodeficiency virus (SIV)-infected macaque model to perform detailed measurements and mathematical modeling during primary infection and during treatment of established infection with the antiretroviral drug (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA). The calculated clearance half-life for productively infected cells during resolution of the peak viremia of primary infection was on the order of 1 day, with slightly shorter clearance half-lives calculated during PMPA treatment. Viral reproduction rates upon discontinuation of PMPA treatment after 2 weeks were approximately twofold greater than those obtained just prior to initiation of treatment in the same animals, likely reflecting accumulation of susceptible target cells during treatment. The basic reproductive ratio (R0) for the spread of SIV infection in vivo, which represents the number of productively infected cells derived from each productively infected cell at the beginning of infection, was also estimated. This parameter quantifies the extent to which antiviral therapy or vaccination must limit the initial spread of virus to prevent establishment of chronic disseminated infection. The results thus provide an important guide for efforts to develop vaccines against SIV and, by extension, human immunodeficiency virus. 相似文献
2.
Storage performance-metrics and benchmarks 总被引:2,自引:0,他引:2
Chen P.M. Patterson D.A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1993,81(8):1151-1165
The metrics and benchmarks used in storage performance evaluation are discussed. The technology trends taking place in storage systems, such as disk and tape evolution, disk arrays, and solid-state disks, are highlighted. The current popular I/O benchmarks are then described, reviewed, and run on three systems: a DECstation 5000/200 running the Sprite Operating System, a SPARCstation 1+ running SunOS, and an HP Series 700 (Model 730) running HP-UX. Two approaches to storage benchmarks-LADDIS and a self-scaling benchmark with predicted performance-are also described 相似文献
3.
DJ Patterson 《Canadian Metallurgical Quarterly》1994,23(2):313-325
Postgastrectomy syndromes are uncommon but, unfortunately, frustrating for both patient and physician, because treatment with prokinetic agents is often of limited benefit. This article examines the evidence for efficacy of available prokinetic drugs in the management of these difficult disorders. 相似文献
4.
5.
Hovius Marjolijn; Kellenbach Marion L.; Graham Kim S.; Hodges John R.; Patterson Karalyn 《Canadian Metallurgical Quarterly》2003,17(1):100
The authors investigated the impact of semantic knowledge on visual object analysis by assessing the performance of patients with semantic dementia on a different-views object matching test and on 2 object decision tests differing, for example, in whether the nonreal items were nonsense objects or chimeras of 2 real objects. On average, the patients scored normally on both the object matching and the object decision test including nonsense objects but were impaired on the object decision test including chimeras; this latter was also the only visual object test that correlated significantly with degree of semantic impairment. These findings demonstrate that object decision is not a single task or ability and that it is not necessarily independent of conceptual knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Emily S. Patterson David D. Woods Richard I. Cook Marta L. Render 《Cognition, Technology & Work》2007,9(3):155-162
Resilience, the ability to adapt or absorb disturbance, disruption, and change, may be increased by team processes in a complex,
socio-technical system. In particular, collaborative cross-checking is a strategy where at least two individuals or groups
with different perspectives examine the others’ assumptions and/or actions to assess validity or accuracy. With this strategy,
erroneous assessments or actions can be detected quickly enough to mitigate or eliminate negative consequences. In this paper,
we seek to add to the understanding of the elements that are needed in effective cross-checking and the limitations of the
strategy. We define collaborative cross-checking, describe in detail three healthcare incidents where collaborative cross-checks
played a key role, and discuss the implications of emerging patterns. 相似文献
7.
8.
9.
SK Patterson JA Tworek MA Roubidoux MA Helvie HA Oberman 《Canadian Metallurgical Quarterly》1997,169(3):709-712
OBJECTIVE: The objective of this study was to describe the mammographic appearance with pathologic correlation of metaplastic carcinoma of the breast. CONCLUSION: Metaplastic carcinomas of the breast are masses with mammographic characteristics of low suspicion because of their histologic appearance. Metaplastic carcinoma should be included in the differential assessment of predominately circumscribed, noncalcified masses revealed on mammography. One salient feature that may distinguish metaplastic carcinomas is the occurrence of a circumscribed portion with a spiculated portion, which is seen in carcinomas that have a significant mixture of metaplastic and invasive carcinoma growth patterns. 相似文献
10.
Neonatal emergencies have become more common as increasingly sophisticated Neonatal Intensive Care Units graduate lower birth-weight babies born at younger gestational ages. These patients present a number of challenges to emergency physicians. They are often discharged with apnea monitors, which generate a high number of false alarms. Neonatal Intensive Care Unit graduates, however, are predisposed to a number of conditions that can result in true episodes of apnea. We present such a case and will discuss the unusual underlying cause of apnea, the utility of apnea monitors, and the need for emergency physicians to be prepared to evaluate and treat these potentially complicated patients. 相似文献