首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6793篇
  免费   243篇
  国内免费   4篇
电工技术   93篇
综合类   3篇
化学工业   940篇
金属工艺   289篇
机械仪表   106篇
建筑科学   330篇
矿业工程   113篇
能源动力   162篇
轻工业   666篇
水利工程   50篇
石油天然气   20篇
无线电   595篇
一般工业技术   1012篇
冶金工业   1446篇
原子能技术   64篇
自动化技术   1151篇
  2023年   45篇
  2022年   56篇
  2021年   143篇
  2020年   95篇
  2019年   133篇
  2018年   160篇
  2017年   147篇
  2016年   192篇
  2015年   140篇
  2014年   201篇
  2013年   400篇
  2012年   281篇
  2011年   343篇
  2010年   271篇
  2009年   277篇
  2008年   294篇
  2007年   289篇
  2006年   263篇
  2005年   194篇
  2004年   190篇
  2003年   153篇
  2002年   171篇
  2001年   101篇
  2000年   115篇
  1999年   100篇
  1998年   352篇
  1997年   224篇
  1996年   190篇
  1995年   113篇
  1994年   113篇
  1993年   136篇
  1992年   73篇
  1991年   66篇
  1990年   58篇
  1989年   66篇
  1988年   34篇
  1987年   53篇
  1986年   56篇
  1985年   54篇
  1984年   61篇
  1983年   42篇
  1982年   42篇
  1981年   44篇
  1980年   47篇
  1979年   37篇
  1977年   66篇
  1976年   82篇
  1975年   32篇
  1974年   38篇
  1973年   38篇
排序方式: 共有7040条查询结果,搜索用时 15 毫秒
1.
2.
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.

Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.

Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.

Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.

Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities.  相似文献   
3.
4.
5.
Modeling ion implantation of HgCdTe   总被引:2,自引:0,他引:2  
Ion implantation of boron is used to create n on p photodiodes in vacancy-doped mercury cadmium telluride (MC.T). The junction is formed by Hg interstitials from the implant damage region diffusing into the MC.T and annihilating Hg vacancies. The resultant doping profile is n+/n-/p, where the n+ region is near the surface and roughly coincides with the implant damage, the n- region is where Hg vacancies have been annihilated revealing a residual grown-in donor, and the p region remains doped by Hg vacancy double acceptors. We have recently developed a new process modeling tool for simulating junction formation in MC.T by ion implantation. The interstitial source in the damage region is represented by stored interstitials whose distribution depends on the implant dose. These interstitials are released into the bulk at a constant, user defined rate. Once released, they diffuse away from the damage region and annihilate any Hg vacancies they encounter. In this paper, we present results of simulations using this tool and show how it can be used to quantitatively analyze the effects of variations in processing conditions, including implant dose, annealing temperature, and doping background.  相似文献   
6.
The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management.  相似文献   
7.
在近期一次SEMI产业策略论坛发表的演讲中,Lam Research Corp.的总裁兼CEO Stephen Newberry认为,半导体产业已经进入了“无利的繁荣时代”。2003年以来,每比特/功能的价格已经比每比特/价格的成本下降得更快,使得整个产业的利润遭到侵蚀。这似乎成为了一个无法维继的市场,随着时间的推移必须进行自我修正才行。  相似文献   
8.
9.
Formaldehyde is used in ruminant feeding for different purposes including the protection of dietary proteins from ruminal degradation. The formaldehyde content of milk of goats fed various levels of formaldehyde-treated soybean oil-meal has been determined by using a sensitive HPLC method. Results showed a significant linear correlation between ingested formaldehyde and formaldehyde concentration in milk. About 0.02% of ingested formaldehyde was excreted in milk, as free formaldehyde.  相似文献   
10.
A central sleep apnea is the absence of respiratory effect, and, thus, the absence of airflow during sleep. Central hypopnea, a related disorder, is also discussed. The sensory component of central sleep apnea; defects involving the integrative and executive neurons; non-neurologic causes of central sleep apneas, including chronic obstructive pulmonary disease and congestive heart failure; diagnosis; treatment; and other topics are reviewed in detail.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号